In some places sulphur is extracted from iron pyrites by one of two methods.
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.
The hardness (6-62) is the same as that of pyrites, and the specific gravity (4.8-4.9) as a rule rather less.
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).
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."
PYRITES, a term applied to iron disulphide when crystallized in the cubic system, but used also in a general sense to designate a group of metallic sulphides of which this mineral is the most characteristic example.
When employed as a group-name the constituent species are distinguished by prefixes: thus the type is called iron pyrites, whilst other species are known as copper pyrites, arsenical pyrites, &c. The original word pyrites (from Gr.
Iron-pyrites was formerly called marcasite, a word variously written marcasin, marchasite, marchesite, marquesite, &c. The two names are now applied to distinct mineral species.
The compound FeS 2 is dimorphous, and the modern practice is to distinguish the cubic forms as pyrites and the orthorhombic as marcasite (q.v.).
Sometimes, however, the term pyrites is loosely applied to both species, and the cubic pyrites is then differentiated by the name "pyrite" - a form which brings the last syllable into harmony with the spelling of the names of most minerals.
Iron pyrites, or pyrite, belongs crystallographically to the parallelfaced hemihedral class of the cubic system.
In many cases it has been formed from other iron oxides, like haematite and magnetite, or by the alteration of pyrites or chalybite.
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.
Iron is found in eastern Tibet in the form of pyrites, and is rudely smelted locally.
After coal and iron the most valuable minerals are zinc, lead, pyrites and copper.
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.