Iron-pyrites come almost entirely from Department.
The table below gives the average production of zinc, argentiferous lead, iron-pyrites and other ores during the quinquennial period 1901f 905.
Iron-pyrites - 297.2 170,312
Their produce has gradually decreased since the 17th century, and is now unimportant, but sulphate of copper, iron pyrites, and some gold, silver, sulphur and sulphuric acid, and red ochre are also produced.
Near Tokat copper pyrites, with iron and manganese, kaolin and coal are found; but most of the copper worked here comes from the mines of Keban Maden and Arghana Maden, on the upper Euphrates and Tigris.
Enclosures of pyrites may give a bluish colour to amber.
Free sulphur may also result from the decomposition of pyrites, as in pyritic shales and lignites, or from the alteration of galena: thus crystals of sulphur occur, with anglesite, in cavities in galena at Monteponi near Iglesias in Sardinia; whilst the pyrites of Rio Tinto in Spain sometimes yield sulphur on weathering.
Copper pyrites (copper), galena (lead), blende (zinc), cinnabar (mercury), &c. Of the sulphates we notice gypsum and anhydrite (calcium), barytes (barium) and kieserite (magnesium).
In some places sulphur is extracted from iron pyrites by one of two methods.
The pyrites is subjected to dry distillation from out of iron or fire-clay tubular retorts at a bright red heat.
Such pyrites sulphur is usually contaminated with arsenic, and conse- quently is of less value than Sicilian sulphur, which is characteristically free from this impurity.
Ruthenium sulphides are obtained when the metal is warmed with pyrites and some borax, and the fused mass treated with hydrochloric acid first in the cold and then hot.
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.
The alum schists employed in the manufacture of alum are mixtures of iron pyrites, aluminium silicate and various bituminous substances, and are found in upper Bavaria, Bohemia, Belgium and Scotland.
The conglomerate bands and quartzites contain large quantities of iron pyrites deposited subsequent to their formation, that in the conglomerates containing the gold.
Of minerals containing this element mention may be made of cassiterite or tinstone, Sn02, tin pyrites, Cu 4 SnS 4 + (Fe,Zn) 2 SnS 4; the metal also occurs in some epidotes, and in company with columbium, tantalum and other metals.
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.
In diameter, leaves the stamps in suspension in water, and passes through a series of troughs in which the heavier mineral is collected; this then passes through a series of washing operations, which leaves a mixture consisting chiefly of tinstone and arsenical pyrites, which is calcined and washed again, until finally black tin containing about 60 to 65% of metal is left.
The outcrop of a metalliferous vein frequently manifests itself as a line of rocks stained with oxide of iron, often honeycombed and porous, the " gossan " or " eisen-hut," the iron oxide of which results from the decomposition of the pyrites, usually present as a constituent of such veins.
As the coal and the associated rocks usually contain pyrites, these springs are often chalybeate.
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).
The difficulty in separating zinc blende from iron pyrites is well known, and probably the most elaborate ore-dressing works ever built have been designed with this end in view.
Neither mechanical nor magnetic concentration can effect much in the way of separation when, as in many complex ores, carbonates of iron, calcium and magnesium replace the isomorphous zinc carbonate, when some iron sulphide containing less sulphur than pyrites replaces zinc sulphide, and when gold and silver are contained in the zinc ore itself.
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.
These are the only certain examples of natural combinations of the metal, the minute, though economically valuable, quantity often found in pyrites and other sulphides being probably only present in mechanical suspension.
Prominent among these are galena and iron pyrites, the former being almost invariably gold-bearing.
Iron pyrites, however, is of greater practical importance, being in some districts exceedingly rich, and, next to the native metal, is the most prolific source of gold.
Magnetic pyrites, copper pyrites, zinc blende and arsenical pyrites are other and less important examples, the last constituting the gold ore formerly worked in Silesia.
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."
One of the greatest difficulties in the treatment of gold by amalgamation, and more particularly in the treatment of pyrites, arises from the so-called " sickening " or " flouring " of the mercury; that is, the particles, losing their bright metallic surfaces, are no longer capable of coalescing with or taking up other metals.
The process was introduced in 1858 by Deetken at Grass Valley, California, where the waste minerals, principally pyrites from tailings, had been worked for a considerable time by amalgamation.
The conversion of silver into the sulphide may be effected by heating with antimony sulphide, litharge and sulphur, pyrites, or with sulphur alone.
Of the rarer bismuth minerals we may notice the following: - the complex sulphides, copper bismuth glance or wittichenite, BiCu 3 S 3, silver bismuth glance, bismuth cobalt pyrites, bismuth nickel pyrites or saynite, needle ore (patrinite or aikinite), BiCuPbS 3, emplectite, CuBiS 2, and kobellite, BiAsPb 3 S 6; the sulphotelluride tetradymite; the selenide guanajuatite, B12Se3, Iv.
Small quantities are occasionally met with in iron pyrites, and hence tellurium is found with selenium in the flue dust, or chamber deposits of sulphuric acid works.
The bottom of the Black Sea is covered by a stiff blue mud in which Sir John Murray found much sulphide of iron,' grains or needles of pyrites making up nearly 50% of the deposit, and there are also grains of amorphous calcium carbonate evidently precipitated from the water.
The divisional planes often contain small films of other minerals, the commonest being calcite, gypsum and iron pyrites, but in some cases zeolitic minerals and galena have been observed.
Pyrites, which yields sulphates by combustion.
An indication of the character of the ash of a coal is afforded by its colour, white ash coals being generally freer from sulphur than those containing iron pyrites, which yield a red ash.
It is known also as arsenopyrite or arsenical pyrites (Ger.
MARCASITE, a mineral with the same chemical composition as pyrites, being iron disulphide FeS2, but crystallizing in the orthorhombic instead of in the cubic system.
Agricola in 1546 under the names Wasserkies or Weisserkies and Leberkies, and it has been variously known as white pyrites, hepatic pyrites, lamellar pyrites, radiated pyrites (German Strahlkies) and prismatic pyrites.
The orthorhombic form of the crystals, as distinct from the cubic form of pyrites, was recognized by Rome de 1'Isle in 1772, though later R.
This frequent twinning gives rise to characteristic forms, with many re-entrant angles, to which the names "spear pyrites" and "cockscomb pyrites" are applied.
Apart from crystalline form, the external characters of marcasite are very similar to those of pyrites, and when distinct crystals are not available the two species cannot always be easily distinguished.
The colour is usually pale bronze-yellow, often rather lighter than that of pyrites; on freshly fractured surfaces of pure marcasite the colour is tin-white, but this rapidly tarnishes on exposure to air.
The hardness (6-62) is the same as that of pyrites, and the specific gravity (4.8-4.9) as a rule rather less.
Many experiments have been made with a view to determining the difference in chemical constitution of marcasite and pyrites, but with no very definite results.
It is a noteworthy fact that whilst pyrites has been prepared artificially, marcasite has not.
Marcasite occurs under the same conditions as pyrites, but is much less common.
Whilst pyrites is found abundantly in the older crystalline rocks and slates, marcasite is more abundant in clays, and has often been formed as a concretion around organic remains.