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quartz

quartz

quartz Sentence Examples

  • The rocks are probably of quartz, i.e.

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  • The rocks are probably of quartz, i.e.

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  • Gold is obtained chiefly from quartz reefs, but there are still some important alluvial deposits being worked.

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  • The greatest development of quartz reefing is found in Victoria, some of the mines being of great depth.

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  • The conglomerates consist almost entirely of pebbles of quartz set in a hard 2 At the Standerton gauge on the Vaal in 1905-1906, a year of extreme drought, the total flow was 8,017,000,000 cub.

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  • from quartz mines.

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  • from quartz mines.

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  • Often they contain quartz and felspar, sometimes pyroxene, amphibole, garnet or epidote.

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  • Well-worn pebbles of amorphous quartz (agate, chalcedony, jasper, &c.) are found in the stratified drift along the western side of the Tertiary region of the state, and from Columbus northward.

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  • AMETHYST, a violet or purple variety of quartz used as an ornamental stone.

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  • The quartz-schists consist of quartz and white mica, and are intimately related to quartzites.

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  • The lodes occur in Silurian metamorphic micaceous schists, intruded by granite, porphyry and diorite, and traversed by numerous quartz reefs, some of which are gold-bearing.

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  • He passed the oscillations to be detected through a fine wire or strip of gold leaf, and over this, but just not touching, suspended a loop of bismuth-antimony wire by a quartz fibre.

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  • He passed the oscillations to be detected through a fine wire or strip of gold leaf, and over this, but just not touching, suspended a loop of bismuth-antimony wire by a quartz fibre.

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  • Molybdenum, in the form of molybdenite (sulphide of molybdenum), is found in Queensland, New South Wales and Victoria, associated in the parent state with tin and bismuth in quartz reefs.

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  • In the south the body is slightly cut by women with small flakes of glass or quartz in zigzag or lineal patterns downwards.

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  • On exposure to heat, amethyst generally becomes yellow, and much of the cairngorm or yellow quartz of jewellery is said to be merely "burnt amethyst."

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  • In the south the body is slightly cut by women with small flakes of glass or quartz in zigzag or lineal patterns downwards.

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  • On exposure to heat, amethyst generally becomes yellow, and much of the cairngorm or yellow quartz of jewellery is said to be merely "burnt amethyst."

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  • The product has a brilliant white fracture, a specific gravity of 4.87, very friable, but harder than quartz or steel.

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  • Veins of amethystine quartz are apt to lose their colour on the exposed outcrop.

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  • There is a considerable export of quartz crystal, commercially known as "Brazilian pebbles," used in optical work.

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  • There have been repeated stories of diamonds obtained from the Finley Mountains (which are volcanic) in the central province, but all specimens sent home, except one, have hitherto proved to be quartz crystals.

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  • There is a considerable export of quartz crystal, commercially known as "Brazilian pebbles," used in optical work.

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  • On the under-side, there are found attached fragments of limestone and quartz, showing that the shingle bed once extended up to it, and that it then formed the original floor.

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  • The prevailing formations appear to be granites which are veined with white quartz, and underlie old sedimentary brown sandstone and limestone formations.

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  • These crystals have, as a rule, very good crystalline form, but the quartz and felspar are often filled with enclosures of glass.

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  • In East Siberia gold is obtained almost exclusively from gravel-washings, quartz mining being confined to three localities, one near Vladivostok and two in Transbaikalia.

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  • Galena occurs in veins in the Cambrian clay-slate, accompanied by copper and iron pyrites, zinc-blende, quartz, calcspar, iron-spar, &c.; also in beds or nests within sandstones and rudimentary limestones, and in a great many other geological formations.

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  • These crystals have, as a rule, very good crystalline form, but the quartz and felspar are often filled with enclosures of glass.

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  • Galena occurs in veins in the Cambrian clay-slate, accompanied by copper and iron pyrites, zinc-blende, quartz, calcspar, iron-spar, &c.; also in beds or nests within sandstones and rudimentary limestones, and in a great many other geological formations.

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  • The company also owns iron mines, limestone and quartz quarries, large iron-works at Domnarfvet and elsewhere, a great extent of forests and saw-mills, and besides the output of the copper mines it produces manufactured iron and steel, timber, wood-pulp, bricks and charcoal.

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  • The difference between schists and gneisses is mainly that the latter have less highly developed foliation; they also, as a rule, are more coarse grained, and contain far more quartz and felspar, two minerals which rarely assume platy or acicular forms, and hence do not lead to the production of a fissile character in the rocks in which they are important constituents.

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  • Celts, of the usual late neolithic type, were generally of green jasper; hoe-blades (looking almost exactly like palaeolithic haches a main) of chert or coarse limestone; hammers of granite; mace-heads, of identical type with the early Egyptian, of diorite and limestone; nails of obsidian or smoky quartz, often beautifully made.

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  • The difference between schists and gneisses is mainly that the latter have less highly developed foliation; they also, as a rule, are more coarse grained, and contain far more quartz and felspar, two minerals which rarely assume platy or acicular forms, and hence do not lead to the production of a fissile character in the rocks in which they are important constituents.

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  • Celts, of the usual late neolithic type, were generally of green jasper; hoe-blades (looking almost exactly like palaeolithic haches a main) of chert or coarse limestone; hammers of granite; mace-heads, of identical type with the early Egyptian, of diorite and limestone; nails of obsidian or smoky quartz, often beautifully made.

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  • Over 70,000 men are employed in the gold-mining industry, more than two-thirds of them being engaged in quartz mining.

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  • deep, and then through a series of remarkable underground caves hollowed out of a quartz mountain and, with their arches and white columns, presenting the appearance of a pillared temple.

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  • Few obsidians are entirely vitreous; usually they have small crystals of felspar, quartz, biotite or iron oxides, and when these are numerous the rock is called a porphyritic obsidian (or hyalo-liparite).

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  • Occasionally the rounded cracks extend from the matrix into some of the crystals especially those of quartz which have naturally a conchoidal fracture.

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  • A dull stony-looking rock results, the vitreous lustre having entirely disappeared, and in microscopic section this exhibits a cryptocrystalline structure, being made up of exceedingly minute grains principally of quartz and felspar.

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  • Lastly, from the Altai region, as well as from the Nerchinsk Mountains, precious stones, such as jasper, malachite, beryl, dark quartz, and the like, are exported.

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  • Flattened crystals of garnet, films of quartz, and needles of tourmaline are not uncommon.

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  • These veins consist of felspar, quartz and mica, often with smaller amounts of other crystallized minerals, such as tourmaline, beryl and garnet; they are worked for mica in India, the United States (South Dakota, Colorado and Alabama), and Brazil (Goyaz, Bahia and Minas Geraes).

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  • Besides the alluvial deposits a little mining is carried on, gold being present in the thin veins of quartz which cross the sandstone.

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  • Throughout the world, primary deposits of tinstone are in or closely connected with granite or acid eruptive rocks of the same type, its mineral associates being tourmaline, fluorspar, topaz, wolfram and arsenical pyrites, and the invariable gangue being quartz: the only exception to this mode of occurrence is to be found in Bolivia, where the tin ore occurs intimately associated with silver ores, bismuth ores and various sulphides, whilst the gangue includes barytes and certain carbonates.

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  • A quartz vein or bed of hard rock may show itself as a sharp ridge or as a well-defined bench; a stratum of soft rock or the line of a great fissure, or the weakening of the strata by an anticlinal fold, may produce a ravine or a deep valley.

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  • At Bendigo in Australia are several shafts between 3000 and 4000, and one, the Victoria Quartz mine, 43 00 ft.

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  • There is a gold mine at Kyaukpazat in the Mawnaing circle of the Kathra district, where the quartz is crushed by machinery and treated by chemical processes.

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  • Electrical furnaces have not as yet been employed for ordinary glass-making on a commercial scale, but the electrical plants which have been erected for melting and moulding quartz suggest the possibility of electric heating being employed for the manufacture of glass.

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  • It is found in the form of oxide (silica), either anhydrous or hydrated as quartz, flint, sand, chalcedony, tridymite, opal, &c., but occurs chiefly in the form of silicates of aluminium, magnesium, iron, and the alkali and alkaline earth metals, forming the chief constituent of various clays, soils and rocks.

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  • Sand consists of grains of quartz or flint, the individual particles of which are large enough to be seen with the unaided eye or readily felt as gritty grains when rubbed between the finger and thumb.

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  • Chemically pure sand is silicon dioxide (SiO 2) or quartz, a clear transparent glass-like mineral, but as ordinarily met with, it is more or less impure and generally coloured reddish or yellowish by oxide of iron.

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  • It may also be accompanied by pyrites, galena, arsenides and antimonides, quartz, calcite, dolomite, &c. It is widely distributed, and is particularly abundant in Germany (the Harz, Silesia), Austro-Hungary, Belgium, the United States and in England (Cumberland, Derbyshire, Cornwall, North Wales).

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  • The quartz reefs which crop out in the granite ranges of the Tehama contain traces of gold.

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  • The Eastern Andes is a magnificent range in the southern part of Peru, of Silurian formation, with talcose and clay slates, many quartz veins and eruptions of granitic rocks.

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  • The gold ores of Peru are usually found in ferruginous quartz.

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  • Quartz porphyry, quartzless porphyry, and granite are largely developed.

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  • Old schists, free from fossils and rich in quartz, overlie it in parallel chains through the whole length of the peninsula, especially in the central and highest ridges, and bear the ores of Chu-goku (the central provinces), principally copper pyrites and magnetic pyrites.

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  • These schist ridges rich in quartz show, to a depth of 20 metres, considerable disintegration.

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  • In the hill country on the borders of Ise, Owari, Mikawa and TOtmi, on the one side, and Omi, Mino and Shinano, on the other, granite frequently forms dark grey and much disintegrated rock-projections above schist and diluvial quartz pebbles.

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  • Thus, for instance, near Nikko in the upper valley of the Daiya-gawa, and in several other places in the neighboring mountains, a granite-porphyry appears with large, pale, flesh-colored crystals of orthoclase, dull triclinic feispar, quartz and hornblende.

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  • Among objects used are a pool of ink in the hand (Egypt), the liver of an animal (tribes of the North-West Indian frontier), a hole filled with water (Polynesia), quartz crystals (the Apaches and the Euahlayi tribe of New South Wales), a smooth slab of polished black stone (the Huille-che of South America), water in a vessel (Zulus and Siberians), a crystal (the Incas), a mirror (classical Greece and the middle ages), the finger-nail, a swordblade, a ring-stone, a glass of sherry, in fact almost anything.

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  • It is the centre of a large gold-field consisting of quartz ranges, with some alluvial deposits, and many of the mines are deep-level workings.

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  • The discovery of alluvial gold in 1851 brought many immigrants to the district; but the opening up of the quartz reefs in 1872 was the principal factor in the importance of Bendigo.

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  • Except in the larger nuggets, which may be more or less angular, or at times even masses of crystals, with or without associated quartz or other rock, gold is generally found bean-shaped or in some other flattened form, the smallest particles being scales of scarcely appreciable thickness, which, from their small bulk as compared with their surface, subside very slowly when suspended in water, and are therefore readily carried away by a rapid current.

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  • (2) More common are the auriferous quartz-reefs - veins or masses of quartz containing gold in flakes visible to the naked eye, or so finely divided as to be invisible.

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  • The Alaska gold was derived almost wholly from the large low-grade quartz mines of Douglas Island prior to 1899, but in that year an important district was discovered at Cape Nome, on the north-western coast.

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  • In all cases the quartz or other vein stuff must be reduced to a very fine powder as a preliminary to further operations.

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  • either (I) by the Mexican crusher or arrastra, in which the grinding is effected upon a bed of stone, over which heavy blocks of stone attached to cross arms are dragged by the rotation of the arms about a central spindle, or (2) by the Chilean mill or trapiche, also known as the edge-runner, where the grinding stones roll upon the floor, at the same time turning about a central upright - contrivances which are mainly used for the preparation of silver ores; but by far the largest proportion of the gold quartz of California, Australia and Africa is reduced by (3) the stamp mill, which is similar in principle to that used in Europe for the preparation of tin and other ores.

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  • At Schemnitz, Kerpenyes, Kreuzberg and other localities in Hungary, quartz vein stuff containing a little gold, partly free and partly associated with pyrites and galena, is, after stamping in mills, similar to those described above, but without rotating stamps, passed through the so-called " Hungarian gold mill " or " quick-mill."

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  • The stuff from the stamps is conveyed to the middle of the muller, and is distributed over the mercury, when the gold subsides, while the quartz and lighter materials are guided by the blades to the circumference and are discharged, usually into a second similar mill, and subsequently pass over blanket tables, i.e.

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  • Chlorine, generally prepared by the interaction of pyrolusite, salt and sulphuric acid, is led from a suitable generator beneath the false bottom, and rises through the moistened ore, which rests on a bed of broken quartz; the gold is thus converted into a soluble chloride, which is afterwards removed by washing with water.

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  • After charging, the barrel is rotated, and when the chlorination is complete the contents are emptied on a filter of quartz or some similar material, and the filtrate led to settling tanks.

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  • In the Eastern province the rocks are mainly quartz, gneiss and granite, with sandstone in Busoga, basalt round Mt Elgon, slate (Busoga) and iron- g stone (Busoga and Bukedi).

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  • Rift valley, overlying a formation of granite, gneiss and quartz.

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  • Gneiss, granite and quartz - the decomposed granite giving the red " African " clay - are the leading features in the formations of the Northern province, of Buganda, and of the Western province, with some sandstone in the littoral districts of Buganda and in Ankole, and eruptive rocks.

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  • The light flesh colour of the feldspar, and the blue of the quartz give it in some places a slight pinkish tint, and it is now much used as a building-stone under the name of ` pink granite.'

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  • Other minerals are emery, limestone and quartz.

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  • The Nahuatl lapidaries had at hand many varieties of workable and beautiful stone - onyx, marble, limestone, quartz and quartz crystal, granite, syenite, basalt, trachyte, rhyolite, diorite and obsidian, the best of material prepared for them by nature; while the Mayas had only limestone, and hard, tenacious rock with which to work it, and timber for burning lime.

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  • The rocks in the Arakan range and its spurs are metamorphic, and comprise clay, slates, ironstone and indurated sandstone; towards the S., ironstone, trap and rocks of basaltic character are common; veins of steatite and white fibrous quartz are also found.

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  • As in other countries, however, the working of quartz reefs gradually compensated for this.

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  • In the mercury experiment the sounding rod was sealed into the dust-tube, which was exhausted of air, and contained only some mercury and some quartz dust to give the heaps.

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  • The alluvial gold-fields were the richest ever opened up, but as these deposits have become exhausted the quartz reefs at deep levels have been exploited, and several mines are worked at depths exceeding 2000 ft.

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  • Cement deposits were discovered in the Black Hills region in 1876 and in the same year the first quartz mill was set up in Deadwood.

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  • The city is the commercial and financial centre of the state (Butte being the mining centre), and is one of the richest cities in the United States in proportion to its population, It has large railway car-shops, extensive smelters and quartz crushers (at East Helena), and various manufacturing establishments; the value of the factory product in 1905 was $1,309,746, an increase of 68.7% over that of 1900.

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  • The surrounding country abounds in goldand silver-bearing quartz deposits, and it is estimated that from the famous Last Chance Gulch alone, which runs across the city, more than $40,000,000 in gold has been taken.

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  • quartz and felspar, which under ordinary conditions form more equidimensional crystals, would assume lenticular forms. In the necessary co-operation of these three causes, viz.

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  • The principal additional ingredient is quartz in minute lens-shaped grains.

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  • By advancing crystallization and increased size of their components, slates pass gradually into phyllites, which consist also of quartz, muscovite and chlorite.

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  • Frequently in districts where slates are much crumpled they are traversed by numerous quartz veins, which have a thickness varying from several inches up to many feet, and may occasionally be auriferous.

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  • Papers published in 1776 were concerned with quartz, alum and clay and with the analysis of calculus vesicae from which for the first time he obtained uric acid.

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  • There appears, however, to be some objection to the use of iridio-platinum for weights, as, owing to its great density (Δ=21.57), the slightest abrasion will make an appreciable difference in a weight; sometimes, therefore, quartz or rock-crystal is used; but to this also there is some objection, as owing to its low density (Δ=2.65) there is a large exposed surface of the mass.

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  • Ornaments of gold and silver, and jewels of polished quartz and green chalchihuite were worn - not only the ears and nose but the lips being pierced for - ornaments.

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  • of Manchester, is a deep pink quartz monzonite, marked with fine black dots, which has a fine texture, takes a good polish and is used for monuments.

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  • A quartz schist, suitable for making whetstones and oilstones, was discovered in 1823 by Isaac Pike at Pike Station, Grafton county, and the Pike Manufacturing Company now owns and operates quarries outside this state also; in 1907 New Hampshire was the principal producer of scythe-stones in the United States, and the total value of whetstones made in 1907 (including the value of precious stones') was $59,870.

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  • It is often associated with blende and pyrites, and with calcite, fluorspar, quartz, barytes, chalybite and pearlspar as gangue minerals; in the upper oxidized parts of the deposits, cerussite and anglesite occur as alteration products.

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  • Wood, when white light is transmitted through a paste made of powdered quartz and a mixture of carbon bisulphide with benzol having the same refractive index as the quartz for yellow light.

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  • In this case small temperature changes alter the refractivity of the liquid without appreciably affecting the quartz.

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  • In this way the existence of bands in the infrared part of the spectrum has been predicted in the case of quartz and detected by experiments on the selective reflection of the material.

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  • There are gold-bearing quartz reefs at Madibi, near Mafeking, where mining began in 1906.

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  • Gold occurs in quartz veins traversing various formations (some as young as Jurassic), and also in gravels, which were for the most part deposited previous to the uplift of the Sierra block.

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  • This mature weathering, resulting in the relatively complete separation of the quartz from the kaolin, and both from the calcium carbonate and other basic materials, implies conditions of rock decay comparable to those of the present time.

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  • Other minerals whose production may be found stated in detail in the annual volume on Mineral Resources of the United States Geological Survey are: natural pigments, felspar, white mica, graphite, fluorspar, arsenic, quartz, barytes, bromine.

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  • The gangue was quartz, very irregularly distributed in bodies often of great sizes, for the most part nearly or quite barren of ore.

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  • A series of quartzites and slates referred to the Cambrian, and holding numerous and important veins of auriferous quartz, characterize its Atlantic or southeastern side, while valuable coal-fields occur in Cape Breton and on parts of its shores on the Gulf of St Lawrence.

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  • We are enabled by means of it to extend materially the range of our observation, especially if the ordinary kinds of glass, which strongly absorb ultraviolet light, are avoided, and, when necessary, replaced by quartz.

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  • At that point, however, quartz and even atmospheric air become strongly absorbent and the expensive fluorspar becomes the only medium that can be used.

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  • The prism may be made of a dense flint glass or of quartz if the ultra-violet is to be explored, or it may be hollow and filled with carbon bisulphide, a-bromnaphthalene or other suitable liquid.

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  • After three days he worked with common electricity, trying glass, heavy optical glass, quartz, Iceland spar, all without effect, as on former trials.

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  • By the operation of meteoric agencies, iron pyrites readily pass into limonite often with retention of external form; and the masses of "gozzan" or "gossan" on the outcrop of certain mineral-veins consist of rusty iron ore formed in this way, and associated with cellular quartz.

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  • It is the commercial centre of the north-western grain and wool-producing district and is also noted for its quartz and alluvial gold-mines.

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  • Quartz Porphyry Pp. Porphyrite d Gr.

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  • It is common in mineral-veins, usually associated with quartz, and is often known to miners as "mundic."

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  • Just as a granite is a conglomerate or mechanical mixture of distinct crystalline grains of three perfectly definite minerals, mica, quartz, and felspar, so iron and steel in their usual slowly cooled state consist of a mixture of microscopic particles of such definite quasiminerals, diametrically unlike.

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  • 26a barren mineral matter, such as quartz, limestone and clay, collectively called " the gangue."

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  • To put the iron contained in iron ore into a state in which it can be used as a metal requires essentially, first its deoxidation, and second its separation from the other mineral matter, such as clay, quartz, &c., with which it is found associated.

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  • those rich in silicic acid, such as quartz and clay, and because the slag is consequently acid, i.e.

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  • The mountains consist here of an ancient laminated micaceous quartzite, which is in parts a flexible sandstone known as itacolumite, and in parts a conglomerate; it is interbedded with clay-slate, mica-schist, hornblende-schist and haematite-schist, and intersected by veins of quartz.

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  • Under all these three conditions the diamond is associated with fragments of the rocks of the country and the minerals derived from them, 'especially quartz, hornstone, jasper, the polymorphous oxide of titanium (rutile, anatase and brookite), oxides and hydrates of iron (magnetite, ilmenite, haematite, limonite), oxide of tin, iron pyrites, tourmaline, garnet, xenotime, monazite, kyanite, diaspore, sphene, topaz, and several phosphates, and also gold.

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  • African locality must be mentioned.; considerable finds were reported in 1905 and 1906 from gravels at Somabula near Gwelo in Rhodesia where the diamond is associated with chrysoberyl, corundum (both sapphire and ruby), topaz, garnet, ilmenite, staurolite, rutile, with pebbles of quartz, granite, vIII.

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  • Among the commonest associates of the diamond are quartz, topaz, tourmaline, rutile, zircon, magnetite, garnet, spinel and other minerals which are common accessory constituents of granite, gneiss and the crystalline schists.

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  • At Sao Joao da Chapada, in Minas Geraes, diamonds occur in a clay interstratified with the itacolumite, and are accompanied by sharp crystals of rutile and haematite in the neighbourhood of decomposed quartz veins which intersect the itacolumite.

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  • It has been suggested that these three minerals were originally formed in the quartz veins.

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  • A typical German find is at Taubach, near Weimar, where almond-shaped stone wedges, small flint knives, and roughly-hacked pieces of porphyry and quartz are found, together with the remains of elephants.

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  • By modern mineralogists the name chalcedony is restricted to those kinds of silica which occur not in distinct crystals like ordinary quartz, but in concretionary, mammillated or stalactitic forms, which break with a fine splintery fracture, and display a delicate fibrous structure.

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  • Chalcedony may be regarded as a micro-crystalline form of quartz.

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  • It is rather softer and less dense than crystallized quartz, its hardness being about 6.5 and its specific gravity 2.6, the difference being probably due to the presence of a small amount of opaline silica between the fibres.

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  • Certain flat oval nodules from a decomposed lava (augite-andesite) in Uruguay present a cavity lined with quartz crystals and enclosing liquid (a weak saline solution), with a movable air-bubble, whence they are called "enhydros" or water-stones.

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  • Their geological formation is metamorphic gneiss, veined with felspar and quartz, and interspersed with reddish porphyrite.

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  • A simple form, which is sometimes referred to as a conical pen dulum, may be con structed with a large sewing needle carrying a galvanometer mirror, suspended by means of a silk or quartz fibre as shown in fig.

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  • occur; parts of Muri, along the north bank of the Benue; and the southern border of the Benue basin, where the hills (consisting of ironstone, quartz and granite) appear rich in minerals.

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  • The soil of the Delta is a dark grey fine sandy soil, becoming at times almost a stiff clay by reason of the fineness of its particles, which consist almost wholly of extremely small grains of quartz with a few other minerals, and often numerous flakes of mica.

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  • This deposit varies in thickness, as a rule, from 55 to 70 ft., at which depth it is underlain by a series of coarse and fine yellow quartz sands, with occasional pebbles, or even banks of gravel, while here and there thin beds of clay occur.

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  • They occur as lines of dunes formed of rounded grains of quartz, and lie in the direction of the prevalent wind, usually being of small breadth as compared with their length; but in certain areas, such as that lying S.W.

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  • The materials are quartz crystal, basalt, porphyry, syenite, granite, volcanic ash, various metamorphics, serpentine, slate, dolomite marble, alabaster, many colored marbles, saccharine marble, grey and white limestones.

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  • The cutting of granite was not only by cleavage and hammer dressing, but also by cutting with harder materials than quartz ~,ch as emery.

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  • Glaze and Glass.From almost the beginning of the prehistoric age there are glazed pottery beads found in the graves: and glazing on amulets of quartz or other stones begins in the middle of the prehistoric. Apparently then glazing went together with the working of the copper ores, and probably accidental slags in the smelting gave the first idea of using glaze intentionally.

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  • The silica was needed quite pure from iron, in order to get the rich blues, and was obtained from calcined quartz pebbles; ordinary sand will only make a green frit.

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  • Feldspar, quartz and granite are quarried in the environs.

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  • Its essential constituents are felspar, quartz and riebeckite - a soda amphibole.

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  • Gold is found both in alluvial and quartz formations, the quartz being especially rich.

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  • Auriferous quartz is worked by a foreign company in its neighbourhood.

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  • The township is the centre of the granite industry of the state; the quarries are near the villages of Westerly and Niantic. The granite is of three kinds: white statuary granite, a quartz monzonite, with a fine even-grained texture, used extensively for monuments; blue granite, also a quartz monzonite and also much used for monuments; and red granite, a biotite granite, reddish grey in colour and rather coarse in texture, used for buildings.'

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  • Quartz mining began as early as 1851.

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  • Quartz veins are very often as good at a depth of 3000 ft.

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  • This is the region of quartz mining.

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  • Chrysoprase, mined near Porterville and near Visalia (Tulare county), is used partly for gems, but more largely (like the vesuvianite found near Exeter, in the same county) for mosaic work; and there are ledges of fine rose quartz in the Coahuila mountains of Riverside county and near Lemon Cove, Tulare county.

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  • Gold was discovered on the Sweetwater river in 1867, and placer and quartz deposits have been found in almost every county in the state.

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  • 5 gram each, and the suspension consisting of a very fine quartz fibre.

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  • The variation of the horizontal force is obtained by the motion of a magnet which is carried either by a bifilar suspension or by a fairly stiff metal wire or quartz fibre.

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  • In the Eschenhagen pattern instrument, in which a single quartz fibre is used for the suspension, two magnets are placed in the vicinity of the suspended magnet and are so arranged that their field partly neutralizes the earth's field; thus the torsion required to hold the magnet with its axis perpendicular to the earth's field is reduced, and the arrangement permits of the sensitiveness being altered by changing the position of the deflecting magnets.

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  • Mag., 1904 [6 ], 7, 393) designed a form of vertical force balance in which the magnet with its mirror is attached to the mid point of a horizontal stretched quartz fibre.

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  • Igneous rocks are not extensively developed; in Wales they form an important feature and occur in considerable thickness; they are represented by lavas of olivine-diabase and by contemporaneous tuffs which are traversed by later granite and quartz felsite.

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  • Quartz porphyry, diabase and diorite appear in the Ardennes.

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  • Minerals produced in small quantities include gypsum, millstones, salt and sandstone, and among those found but not produced (in 1902) in commercial quantities may be mentioned allanite, alum, arsenic, bismuth, carbonite, felspar, kaolin, marble, plumbago, quartz, serpentine and tin.

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  • It generally consists of limestone, or of mixed limestone and clay, or of sand and clay, or of gravel, with here and there flint and rolled quartz.

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  • The subsoils of some of the other districts (Cotes and St Emilion) contain much stone in the shape of flint and quartz.

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  • The finest wines of the Medoc and Graves are largely grown on a mixture of gravel, quartz and sand with a subsoil of alios or clay.

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  • The soil varies considerably in nature, but consists mostly of gravel, quartz, limestone and sand on the surface, and of clay and alios beneath.

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  • In the north of Bundelkhand the prevailing rock is gneiss and quartz.

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  • The quartz takes the shape of long serrated ridges, which are in many places a characteristic feature of the landscape.

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  • This conversion is effected by allowing the ferrous chloride liquors slowly to descend a tower, filled with pieces of wood, coke or quartz, where it meets an ascending current of chlorine.

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  • The needle, a piece of paddle-shaped paper thinly coated with silver foil, is suspended by a quartz fibre, its extreme lightness making it possible to use a very feeble controlling force without rendering the period of oscillation unduly great.

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  • To facilitate the communication of the charge to the needle, the quartz fibre and its attachments are rendered conductive by a thin film of solution of hygroscopic salt such as calcium chloride.

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  • The upper end of the quartz fibre is rotated by a torsion head, and a metal cover serves to screen the instrument from stray electrostatic fields.

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  • With a quartz fibre 0.009 mm.

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  • By using a quartz fibre of about half the above diameter the sensitiveness was much increased.

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  • Of these the chief are Poole's Hole, a vast stalactite cave, about half a mile distant; Diamond Hill, which owes its name to the quartz crystals which are not uncommon in its rocks; and Chee Tor, a remarkable cliff, on the banks of the Wye, 300 ft.

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  • The rock is a very compact and fine-grained mixture of felspar, quartz and mica, often graduating to mica schist, quartzite and gneiss.

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  • There are, moreover, some rich gold quartz reefs in the neighbourhood.

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  • To him is also due the discovery of the power of rotatory polarization exhibited by quartz, and last of all, among his many contributions to the support of the undulatory hypothesis, comes the experimentum crucis which he proposed to carry out for comparing directly the velocity of light in air and in water or glass.

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  • Lead, wolfram, antimony and auriferous quartz exist in the districts of Coimbra, Evora, Beja and Faro.

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  • 17, except that two slit-like openings of equal length allowed the light to pass, and that the light was that of the electric arc passed through a quartz prism and casting a powerful spectrum on the plate.

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  • The upper slit was covered with glass, the lower with quartz.

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  • The lower area of bactericidal action extends much farther to the right, because the quartz allows more ultra-violet rays to pass than does glass.

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  • The hard ore is siliceous, and fine crystallized specimens occur in association with smoky quartz.

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  • The dazzling white effect of their peaks is produced, not by snow, as among the Himalayas, but by enormous masses of vitreous rose-coloured quartz.

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  • Many of them are mere heaps of sand and stone; others consist of huge masses of quartz.

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  • Numerous quartz reefs occur both in the Silurian and Ordovician rocks.

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  • The yield of gold from quartz mines was in 1904 II dwt.

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  • In the Wallega district are veins of gold-bearing quartz, mined to a certain extent.

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  • QUARTZ, a widely distributed mineral species, consisting of silicon dioxide, or silica (S102).

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  • The name quartz is an old German word of uncertain origin: it was used by G.

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  • Quartz is a mineral which is put to many uses.

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  • Fused quartz has recently been used for the construction of lenses and laboratory vessels, or it may be drawn out into the finest elastic fibres and used for suspending mirrors, &c., in physical apparatus.

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  • Buhrstone, a cellular variety of chalcedonic quartz from the Tertiary strata of the Paris basin, is largely used for millstones.

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  • Quartz is a valuable grinding and polishing material, and is used for making sandpaper and scouring-soap. It is also largely used in the manufacture of glass and porcelain, "silver sand" being a pure quartz sand.

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  • Quartz crystallizes in the trapezohedral-hemihedral class of the rhombohedral division of the hexagonal system.

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  • are common and sometimes very puzzling, but they can always be orientated by the aid of the very characteristic striations, on the prism faces, which serve also to distinguish quartz from other minerals of similar appearance.

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  • 4 and 5), which indicate the true degree of symmetry of quartz, are of comparatively rare occurrence except on crystals from certain localities.

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  • Numerous other faces have been observed on crystals of quartz, but they are of rare occurrence.

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  • The basal plane, so common on calcite and many other rhombohedral minerals, is of the greatest rarity in quartz, and when present only appears as a small rough face formed by the corrosion of the crystal.

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  • Twinned crystals of quartz are extremely common, but are complex in character and can only be deciphered when the faces s and x are present, which is not often the case.

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  • The pyro-electric characters of quartz are closely connected with its peculiar type of symmetry and especially with the three uniterminal dyad axes.

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  • A similar distribution of electric charges is produced when a crystal is subjected to pressure; quartz being thus also piezo-electric. Etched figures, both natural and artificial (in the latter case produced by the action of hydrofluoric acid), on the faces of the crystals are in accordance with the symmetry, and may serve to distinguish leftand righthanded crystals.

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  • In its optical characters, quartz is also of interest, since it is one of the two minerals (cinnabar being the other) which are circularly polarizing.

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  • A ray of plane-polarized light traversing a right-handed crystal of quartz in the direction of the triad axis has its plane of polarization rotated to the right, while a left-handed crystal rotates it to the left.

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  • thick, cut perpendicular to the principal axis of a quartz crystal, rotates the plane of yellow (D) light through 22°, and of blue (G) light through 43°.

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  • Superimposed sections of rightand left-handed quartz, as may sometimes be present in sections of twinned crystals, exhibit Airy's spirals in the polariscope.

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  • The indices of refraction of quartz for yellow (D) light are co = I.5442 and e = I.

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  • Quartz has a hardness of 7 (being chosen as No.

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  • Many peculiarities of the growth of crystals are well illustrated by the mineral quartz.

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  • Thus in "ghost quartz," in which one crystal is seen inside another, the stages of growth are marked out by thin layers of enclosed material.

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  • In "capped quartz" these layers are thicker, and the successive shells of the crystal may be easily separated.

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  • "Sceptre quartz," in which a short thick crystal is mounted on the end of a long slender prism, indicates a change in the conditions of growth.

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  • Enclosures of other minerals (rutile, chlorite, haematite, gothite, actinolite, asbestos and many others) are extremely frequent in crystals of quartz.

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  • Crystals of quartz are usually attached at one end to their rocky matrix, but sometimes, especially when embedded in a soft matrix of clay, gypsum or salt, they may be bounded on all sides by crystal faces (fig.

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  • The characters as given above apply more particularly to crystals of quartz, but in the various massive and compact varieties the material may be quite different in general appearance.

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  • Further, these varieties may be of almost any colour, whereas transparent crystals have only a limited range of colour, being either colourless (rock-crystal), violet (amethyst), brown (smoky quartz) or yellow (citrine).

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  • Quartz occurs as a primary and essential constituent of igneous rocks of acidic composition such as granite, quartz-porphyry and rhyolite, being embedded in these either as irregularly shaped masses or as porphyritic crystals.

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  • It is also a common constituent, as irregular grains, in many gneisses and crystalline schists, a quartz-schist being composed largely of quartz.

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  • Extensive veins of quartz are especially frequent in schistose rocks.

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  • In mineral veins and lodes crystallized quartz is usually the most abundant gangue mineral; the crystals are often arranged perpendicular to the walls of the lode, giving rise to a "comby" structure.

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  • Quartz being a mineral very resistant to weathering agencies, it forms the bulk of sands and sandstones; and when the sand grains are cemented together by a later deposit of secondary quartz a rock known as quartzite results.

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  • Pseudomorphous quartz, i.e.

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  • quartz replacing other minerals, is of frequent occurrence, and as a petrifying material replacing organic remains it is often met with.

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  • As a deposit from hot springs, quartz is much less common than opal.

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  • Crystals of quartz may be readily prepared artificially by a number of methods; for example, by heating glass or gelatinous silica with water under pressure.

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  • Geological research shows that the land surrounding the lake consists of gneiss, quartz and schistose rocks, covered, in the higher regions, with marl and red clay, and in the valleys with a rich black loam.

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  • The diamonds of this district are noted for their purity and lustre, and are generally associated with other crystals - garnets, agates, quartz and chalcedonies.

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  • Its specific gravity is 2.6 or only a little less than that of crystalline quartz.

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  • Microscopic sections show that flint is very finely crystalline and consists of quartz or chalcedonic silica; colloidal or amorphous silica may also be present but cannot form any considerable part of the rock.

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  • The soil is quartz sand and is chiefly covered with heather and brushwood.

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  • The gneiss is mostly grey, but occasionally pinkish, its essential constituents (felspar and quartz) being almost always associated with dark mica (biotite) and hornblende in variable quantity.

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  • The following precious stones are reported: corundum (rubies and sapphires), beryl, topaz, zircon, garnet, amazon-stone, tourmaline, often in large crystals, and variously coloured quartz, also often found in crystals of great size.

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  • When, however, a plate of quartz is used in this experiment, the light is coloured and is in no case cut off by the analyser, the tint, however, changing as the analyser is rotated.

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  • Biot further ascertained that this rotation of the plane of polarization varies as the distance traversed in the plate and very nearly as the inverse square of the wave-length, and found that with certain specimens of quartz the rotation is in a clockwise or right-handed direction to an observer receiving the light, while in others it is in the opposite direction, and that equal plates of the rightand lefthand varieties neutralize one another's effects.

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  • Since the two circular streams have different speeds, Fresnel argued that it would be possible to separate them by oblique refraction, and though the divergence is small, since the difference of their refractive indices in the case of quartz is only about o 00007, he succeeded by a suitable arrangement of alternately rightand left-handed prisms of quartz in resolving a plane-polarized stream into two distinct circularly polarized streams. A similar arrangement was used by Ernst v.

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  • If in the interference experiment with Fresnel's mirrors or biprism the slit be illuminated with white light that has passed through a polarizer and a quartz plate cut perpendicularly to the optic axis, it is found on analysing the light that in addition to the ordinary central set of coloured fringes two lateral systems are seen, one on either side of it.

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  • According to Fresnel's explanation the light in each of the interfering streams consists of two trains of waves that are circularly polarized in opposite direction and have a relative retardation of phase, introduced by the passage through the quartz: the central fringes are then due to the similarly polarized waves; the lateral systems are produced by the oppositely polarized streams, these on analysation being capable of interfering.

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  • Righi has, however, pointed out that this experiment may be explained by the fact that the function of the quartz plate and analyser is to eliminate the constituents of the composite stream of white light that mask the interference actually occurring at the positions of the lateral systems of fringes, and that any other method of removing them is equally effective.

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  • In fact, the lateral systems are obtained when a plate of selenite is substituted for the quartz.

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  • On these principles Airy, by an elaborate mathematical investigation, successfully explained the interference patterns obtained with plates of quartz perpendicular to the optic axis.

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  • This is a plate made of two equal wedges of quartz, that can be moved over one another so as to vary its thickness, and are cut so that the faces of the plate are parallel to the optic axis, which in the first wedge is perpendicular and in the second is parallel to the refracting edge.

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  • Soda light, first sifted by passage through a plate of potassium bichromate, traverses in succession a lens, a Nicol's prism, and a glass plate half covered with a half-wave plate of quartz, that is cut parallel to the optic axis and has its principal section inclined at a small angle to that of the prism.

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  • The telescope must be focussed on the edge of the quartz plate, and in order that all points of the field may be illuminated by the same part of the source, the flame must be so placed that its image is thrown by the lens on the diaphragm of the object glass of the telescope.

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  • The former consists of two semicircular plates of quartz, perpendicular to the optic axis and of opposite rotations, placed so as to have a common diameter and having such a thickness that each rotates the plane of polarization of mean yellow light through the same multiple of 90°.

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  • This is made of two plates of quartz, cut normally to the optic axis and of opposite rotations, placed the one in front of the other: the thickness of the one plate is fixed, while that of the other can be varied, as it is formed of two equal prisms that can be moved over one another along their common face.

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  • When the plates are of equal thickness, their combined effect is nil, but by adjusting the second, a rotation in the one or the other direction may be introduced, a scale attached to one prism and a vernier to the other giving the thickness of the resultant quartz plate.

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  • In order to correct this, the light after analysation is passed through another plate of quartz and then the sensitive tint may be more or less restored by cutting off some colour, the same for the whole field, by a Nicol's prism placed in the eyepiece of the telescope.

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  • Soleil's saccharimeter, as its name implies, is designed for the study of solutions of sugar, and it is clear that it will only work satisfactorily with active media that have nearly the same rotary dispersion as quartz.

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  • Since glass does not transmit the ultra-violet light, quartz is used, but such lenses can only be spherically corrected and not chromatically.

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  • These mountains consist of detached remnants of a sheet of quartz conglomerates, interbedded with sandstones, containing crinoid stems and obscure brachiopods.

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  • The Jurassic and Cretaceous formations, which in the Southern Cordillera are situated outside of the range to the east, form to a considerable extent the mass of the great range, together with quartz porphyry, the Tertiary, granite and other eruptive rocks, which have been observed along all the chain in South America up to Alaska in the north.

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  • If any rock be taken (even a piece of pure quartz) and crushed to a very fine powder, it will show some of the peculiarities of clays; for example, it will be plastic, retentive of moisture, impermeable to water, and will shrink to some extent if the moist mass be kneaded, and then allowed to dry.

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  • Quartz, for example, has little or no cleavage, and is not attacked by the atmosphere.

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  • They are principally finely divided quartz, epidote, zoisite, rutile, limonite, calcite, pyrites,.

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  • These sediments are fine and tenacious; their principal components, in addition to clay, being small grains of quartz, zircon, tourmaline, hornblende, felspar and iron compounds.

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  • They show that clay rocks contain abundant very small grains of quartz (about o oi to o 05 mm.

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