The oldest rocks of Elba consist of schist and serpentine which in the eastern part of the island are overlaid by beds containing Silurian and Devonian fossils.
It is not volcanic, but consists of argillaceous schist and quartzite.
Archean rocks - gneiss, schist and granite - cover large areas through which the Nile cuts its way in alternate narrow gorges and open reaches.
Graphite occurs mainly in the older crystalline rocks - gneiss, granulite, schist and crystalline limestone - and also sometimes in granite: it is found as isolated scales embedded in these rocks, or as large irregular masses or filling veins.
They consist of gneiss, mica-schist, quartzites, crystalline limestones and conglomerates.
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.
Archean Great Schist Series (Mona, Kitchi, Keewatin, Quinnissec; Lower Huronian of some L authors).
The rocks of the granitoid series appear as great masses in the schist series, and in some places form great protruding bosses.
Nearly all known sorts of schist are represented in the schistose nart of the system.
The commoner sorts of rock in the several Huronian systems are quartzite and slate (ranging from shale to schist); bi~t limestone is not wanting, and igneous rocks, both intrusive and extrtisive, some metamorphic and some not, abound.
Conway schist Amherst schist - ~.-5ooo (~)
Brinfield fibrolite-schist J
Goshen schist 2000, , (?)
Hawley schist 2000 ft.
Savoy schist 5000, , ?)
Rowe schist 4000, , (?)
Hoosic schist 1500, , (?)
Gneiss & Mica Schist A-G.
The oldest rocks are gneiss, schist and quartzite, the schist often containing gold.
The water which has found its way through the granitic sand flows over the surface of the mica schist and settles in the hollows, and by sinking wells to the solid rock a supply of water can generally be obtained.
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.
Chlorite-schist, &c. Diamond has also been reported from kimberlite " pipes " in Rhodesia.
They consist chiefly of gneiss and schist, with granite and other eruptive rocks.
The island is composed of marble, though gneiss and mica-schist are to be found in a few places.
Archean gneiss, Cambrian sandstone, Silurian quartzite, limestone and schist, Jurassic sandstone and limestone, Cretaceous sandstone, and Tertiary basalts, gabbros, and granitic rocks all enter into the composition of the islands.
The Eastern Cordillera is composed of gneiss, mica and chlorite schist and other crystalline rocks of ancient date; the Western Cordillera, on the other hand, is formed of porphyritic eruptive rocks of Mesozoic age, together with sedimentary deposits containing Cretaceous fossils.
The oldest rocks consist of gneiss and schist, penetrated by dikes and bosses of granite, syenite, porphyry and other intrusive rocks.
In the Black River Mountains, at a height of about 1200 ft., there is a clay-slate; and near Midlands, in the Grand Port group of mountains, a chloritic schist occurs about 1700 ft.
This schist is much contorted, but seems to have a general dip to the south or south-east.
The oldest rocks exposed are gneiss, talc-schist and serpentine, with intrusive masses of gabbro and diabase.
At Rammelsberg in the Harz it forms a bed in argillaceous schist, and at Mansfeld in Thuringia it occurs in the Kupferschiefer with ores of nickel and cobalt.
The mining product next in value to coal in 1908 was copper, taken chiefly in Carbon county in a zone of brecciated quartzite underlying schist, the original ore being chalcopyrite, with possibly some pyrite, a secondary enrichment, which has produced important bodies of chalcocite in the upper workings, but these are replaced by chalcopyrite at greater depth.
The soil is a peculiar clay-schist, on or alternating with granite, and it is to the peculiar conditions of climate and soil that port owes its remarkable qualities of colour, body and high flavour.
The rock is a very compact and fine-grained mixture of felspar, quartz and mica, often graduating to mica schist, quartzite and gneiss.
Along the coast lies a belt of granite and schist overlaid unconformably by Cretaceous and Tertiary deposits; inland the mountains are formed chiefly of folded Mesozoic beds, together with volcanic rocks of later date.
This was little more than a small platform of green schist with a sacred tree and an altar, and perhaps later a wooden icon (image), the whole enclosed in a temenos: but, as is proved by a great treasure of objects in precious and other metals, ivory, bone, crystal, paste, glass, terra-cotta and other materials, found in 1904-1905, partly within the platform on which the cult-statue stood and partly outside, in the lowest stratum of deposit, this early shrine was presently enriched by Greeks with many and splendid offerings of Hellenic workmanship. A large number of electron coins, found among these offerings, and in style the earliest of their class known, combine with other evidence to date the whole treasure to a period considerably anterior to the reign of Croesus.
It is also a common constituent, as irregular grains, in many gneisses and crystalline schists, a quartz-schist being composed largely of quartz.
Among the industries of the town are the extraction of oil from the bituminous schist obtained in the neighbourhood, leather manufacture, metal-founding, marble-working, and the manufacture of machinery and furniture.
Part of the rock is schist, but the greater portion limestone, similar in physical qualities to the Carboniferous limestone of Great Britain.
Fuming or Nordhausen Oil of Vitriol, a mixture or chemical com pound of H 2 SO 4, with more or less S03, has been made for centuries by exposing pyritic schist to the influence of atmospheric agents, collecting the solution of ferrous and ferric sulphate thus formed, boiling it down into a hard mass ("vitriolstein") and heating this to a low red heat in small earthenware retorts.
Near Kempoch point is a monolith of mica-schist, 6 ft.
They form an interesting and bleak moorland between Cookstown and Omagh, extending north-eastward into Slieve Gallion in county Londonderry, and consist fundamentally of mica-schist and gneiss, affected by earth-pressures, and invaded by granite near Lough Fee.
- This region, nearly coincident with the mountainous upper portion of the island, is chiefly composed of the following crystalline rocks: gneiss, which is the most common of them all, quartzite and quartz-schist, with occasional beds of crystalline limestone and mica-schist, although this latter rock is very rare.
Red and grey sandstones, hornblende and argillaceous schist are found in the mountains, porphyry and basaltic rocks also occur; sulphur and fuller's earth are worked.
Built partly on the low ground along the edge of the bay and partly on the hill to the north (a compact mass of mica schist), the city with its white houses enclosed by white walls runs up along natural ravines to the castle of the Heptapyrgion, or Seven Towers, and is rendered picturesque by numerous domes and minarets and the foliage of elms, cypresses and mulberry trees.
Sulphur is obtained near Apt (Vaucluse) and in a few other localities of south-eastern France; bituminous schist near Autun (Sane-et-Loire) and Buxires (Allier).
Granite is the most widely spread of the crystalline rocks; but dikes of various kinds occur, and gneiss, schist and marble are also met with.
Tremolite-schist and anthophyllite-schist are in nearly all cases the representatives of the ultra-basic igneous rocks such as peridotite in regions of high metamorphism.
Occasionally serpentines become sheared without yielding talcose minerals; they are then known as serpentine-schist and antigoriteschist, the latter being tough leek-green rocks, more or less transparent.
The eyes in both cases were inlaid, those of the lions with red jasper, white shell and blue schist: this imitation of the eyes in stone as well as metal figures was a feature common to both arts, which were at this time assuredly not without direct or indirect connexion.
The mineral wealth of the department is considerable, including coal as well as manganese and bituminous schist; plaster, building stone and hydraulic lime are also produced.
Bergeron has shown that the gneiss and schist which form so much of the chain consist, in part at least, of metamorphosed Cambrian beds.
Various minerals are employed in the manufacture of alum, the most important being alunite or alum-stone, alum schist, bauxite and cryolite.
The oldest rocks consist of granite and schist, penetrated by intrusive dykes, and upon this foundation rest the flat-lying sedimentary deposits, beginning with a sandstone like the Nubian sandstone of Egypt.
These they call respectively the southern schist range, the northern schist range, and the snow range, the last consisting mainly of old crystalline massive rocks.
The granite forms the prevailing rock in valleys of erosion.
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.
There are several series of parallel beds, interstratified with quartzite and schist, the most important being the "main reef" series.
These schist ridges rich in quartz show, to a depth of 20 metres, considerable disintegration.