Copper pyrite

“ All these yield their copper in solution on boiling with hydrochloric acid.
The sulphides are more abundant. Copper pyrites (or yellow ore) , erubescite (or purple ore) , and chalcocite (or grey ore) are the most important. Iron pyrites generally carries copper and is frequently associated with the above-mentioned minerals. These are all attacked by nitric acid. They nearly all contain a small quantity of organic matter, and frequently considerable quantities of lead, zinc, silver, gold, arsenic, bismuth, &c. ”

“ The sulphide of iron, pyrite, occurs in many crystalline rocks; but, owing to the difficulty of separating the iron and sulphur, is not used as an ore of iron. The mineral much resembles in external appearance a yellow ore of copper, called chalcopyrite, from which it may be distinguished in that it will strike fire with steel. A specimen of pyrites containing large crystals is an interesting subject of study. ”

“ In Ontario and Quebec there are a number of pyrite mines where some of the pyrite contains considerable copper. Most of the pyrite is shipped to the United States, where the copper is recovered, refined and sold.
The production of Canada is growing, and the country will become of increasing importance as a source of copper. Known reserves are larger [239] in proportion to output than in the United States and there will probably be important developments of new districts. The northern British Columbia region is of exceptional promise. ”

“ After one or two days the magistral is added; this is copper vitriol and salt, or rich oxidized copper ores mixed with pyrites which has been roasted with salt, or simply copper pyrites which has been so roasted. The quantity of magistral required varies according to the season, the temperature, and the quantity of the ore; it usually ranges from 1⁄2 to 1 per cent. Its function is to cause certain reactions with the salt and the sulphide of silver and promote the formation of amalgam. Too much of it causes too high a temperature in the mass, particularly in winter ”

“ It occurs in nature as the mineral melanterite, either crystalline or fibrous, but usually massive; it appears to have been formed by the oxidation of pyrite or marcasite. It is manufactured by piling pyrites in heaps and exposing to atmospheric oxidation, the ferrous sulphate thus formed being dissolved in water, and the solution run into tanks, where any sulphuric acid which may be formed is decomposed by adding scrap iron. By evaporation the green vitriol is obtained as large crystals. The chief impurities are copper and ferric sulphates ”

“ Pyrite is very commonly found in vein and replacement deposits of gold, silver, copper, lead, and zinc. In the Mississippi valley it is extracted as a by-product from the lead and zinc ores, and in the Cordilleran region large quantities of by-product pyrite could easily be produced if there were a local demand. The pyrite deposits of the Appalachian region are chiefly lenses in schists; they are of uncertain origin though some are believed to [Pg 109] have been formed by replacement of metamorphosed limestones and schists. ”

“ Infusible by the blow-pipe even with borax, and does not by strong ignition impart any colour to it or to potash; not magnetic, even in fine powder, nor after being heated red hot on charcoal, and in contact with burning grease.
Many specimens decrepitate violently under the blow-pipe. When heated on coals in pieces of considerable size, they often explode with a smart report, and are thrown in fragments sometimes several yards from the fire.
Gangue quartz; accompanying minerals in the same vein, native bismuth, native silver, galena, iron and copper pyrites, much magnetic pyrites, blende, &c. ”

“ One gram of iron pyrites yields about 11 grams of lead. One gram of copper pyrites, blende, fahlerz, or mispickel, yields 7 or 8 grams of lead, whilst 1 gram of antimonite will give 6, and 1 gram of galena only a little over 3 grams. It is evident that if an ore carries much of these sulphides, the quantity of lead reduced will be very much larger than that required for an assay. To counteract this effect nitre is added; 1 gram is added for each 4 grams of lead in excess of that required. ”

“ 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. ”

“ Their average copper content is 2·9 per cent. The chief mines are the Calumet and Hecla, the Tamarack and the Atlantic, all situated on one ore chute measuring 3 miles in length, and worked to a depth of 4,000 feet.
Sulphide Ores: Chalcopyrite (Copper Pyrites) is by far the most widely distributed ore of copper, and furnishes the greater proportion of the world’s supply.
The formula when pure is Cu2S. Fe2S3 (Cu 34·4, Fe 30·5, and S 35·1 per cent.) , but usually the ore is not in this condition, being mechanically mixed with large quantities of iron pyrites, and very often with pyrrhotite. ”

“ The sulphate, oxide or chlorides, which are obtained from the sulphuretted ores, are lixiviated and the metal precipitated in the same manner as we have previously described.
The metal so obtained is known as “cement” copper. If it contains more than 55% of copper it is directly refined, while if it contains a lower percentage it is smelted with matte or calcined copper pyrites. The chief impurities are basic salts of iron, free iron, graphite, and sometimes silica, antimony and iron arsenates. Washing removes some of these impurities, but some copper always passes into the slimes. ”

“ Long descriptions of copper smelting in India are found in Science Gleanings, pp. 380 et seq., No. 36, Dec. 1831, Calcutta, and in Percy (Metall. p. 387) ; the latter by Mr. H. F. Blanford, of the Geol. Survey, who made especial studies in Himalayan Sikkim and the Nepaulese Tirhai. The workmen, who are of low caste, win the stone in small blast-furnaces about three feet high, burning charcoal and cow-chips. They work not only the easily reducible carbonates, but sulphuretted ores, copper pyrites, with a mixture of mundic (iron pyrites) . ”

“ Argentiferous galena occurs at Sala in limestone, surrounded by granulite, and at Guldsmedshytta (province of Örebro) in dark hälleflinta. Copper pyrites occurs at Falun in mica-schists, surrounded by hälleflinta. Zinc blende occurs in large masses at Ammeberg, near the northern end of Lake Vetter. The cobalt ore consists of cobalt-glance (Tunaberg in the province of Södermanland) and of linneite (at Gladhammar, near Vestervik) . The nickel ore of Sweden is magnetic pyrites, containing only a very small percentage of nickel. ”

“ The richest deposits of native copper are those of Lake Superior, in North America. More frequently and more abundantly it occurs as an ore, e.g. red oxide, black oxide, green carbonate of copper or mal′achite, blue carbonate of copper, vitreous sulphide of copper, purple copper, copper pyrites, or yellow copper ore, with sulphur, antimony, or arsenic, and other metals (true grey copper ore or fah′lerz) , as an impure hydrated silicate (chrys′ocolla) , and as an impure hydrated oxychloride (atac′amite) . The most abundant and important ore is copper pyrites. ”

“ It might perhaps have been, to some extent, advantageously enlarged; although, it is true, the author refers us to the particular minerals for individual instances; still it might have been well to have illustrated the general principles by a few well-chosen instances, e. g. how, by the blowpipe, galena is distinguished from sulphuret of antimony; carbonat of lead from sulphat of barytes, or carbonat of lime; garnet from titanium; plaster of Paris from soapstone, &c.; and, among trials in the moist way, how by nitric acid and ammonia, iron pyrites is distinguished from copper pyrites ”

“ That is to say, you can scratch gold with a common knife. Now, iron pyrites is harder than steel, and therefore a knife will fail to scratch it. Gold and iron pyrites, therefore, need never be mistaken for each other by any man who has a piece of steel about him. Copper pyrites can be scratched with steel. But then there is another very familiar property of gold, by which, in this case, it can be distinguished. Gold is very malleable ”

“ The most recently opened parts develop a very high temperature owing to the oxidation of the copper pyrites, and in “El Purgatorio,” as it is called, one finds it difficult to breathe for a moment until a slight effort of will forces the lungs to take in the hot air. ”

“ The very great variety of purposes for which the metal called copper is used, renders it one of the most valuable productions of this country, and several very important manufactures would be incomplete without it, since it is the principal material of which many large vessels are formed, and is also largely employed as an alloy for other metals. Although the metal is sometimes found in a pure or native state, its most abundant ore is that known as copper pyrites, of which there are many kinds. ”

“ Copper prepared by the hydrometallurgical method.—One of the oldest processes of this kind, is that known as the ‘cementation’ method, and consists in precipitating copper from a solution of the sulphate of the metal, by means of metallic iron. In some mines solutions of the sulphate are met with occurring naturally, in others they are prepared artificially by treating poor ores containing oxide of copper, with sulphurous acid or diluted sulphuric acid, and sometimes by roasting copper pyrites and afterwards washing them with water to extract the resulting sulphate. ”

“ The sulphides of copper generally occur in chemical combination with the sulphides of iron. [3] These copper-sulphur compounds (copper pyrites CuFeS2, variegated copper ore Cu3FeS3, &c.) generally occur in veins in a rock gangue.
The extraction of copper from its oxide ores does not present any difficulty, because the copper, when ignited with charcoal and melted, is reduced from the impurities which accompany it. This mode of smelting copper ores is carried on in cupola or cylindrical furnaces, fluxes forming a slag being added to the mixture of ore and charcoal. ”

“ Weathering is a very slow, and, therefore, an expensive process; moreover, the entire conversion is only accomplished after a number of years. Calcination is only advisable for ores which contain relatively much iron pyrites and little copper pyrites. Also, however slowly the calcination may be conducted, there is always more or less copper sulphide left unchanged, and some copper oxide formed. Calcination with ferrous sulphate converts all the copper sulphide into sulphate. Heap roasting has been successfully employed at Agordo, in the Venetian Alps, and at Majdanpek in Servia. ”

“ Beat with a stone on copper pyrites, and it immediately begins to crumble. No acid, by itself, can affect gold; but a mixture of one part nitric, and four parts muriatic acid, is called Aqua Regia, because in this mixture gold does dissolve. ”

“ Determination of Copper in Copper Pyrites.—Powder, dry, and weigh up 20 grams of the ore. Mix with 20 grams each of powdered lime and fluor, 15 grams each of powdered glass and borax, and 5 or 10 grams of nitre. Transfer to a large Cornish crucible and fuse under a loose cover at a high temperature for from 15 to 20 minutes. When fluid and tranquil pour into a mould. When the slag has solidified, but whilst still hot, quench by dipping two or three times in cold water. ”

“ Its composition is Cu3FeS3. But the most common and widely-distributed copper ore is copper pyrites, which crystallises in regular octahedra; it has a metallic lustre, a sp. gr. of 4·0, and yellow colour. Its composition is CuFeS2. It must be remarked that the sulphurous ores of copper are oxidised in the presence of water containing oxygen in solution, and form cupric sulphate, blue vitriol, which is easily soluble in water. If this water contains calcium carbonate, gypsum and cupric carbonate are formed by double decomposition: CuSO4 + CaCO3 = CuCO3 + CaSO4. ”

“ Localities.—Found in slate and limestone rocks. Centreville, Coulterville, New Idria and New Almaden, and Lake and San Luis Obispo Counties, California; Idaho.
22.—Cobalt Pyrites.
Occurs crystallized and massive; does not scratch glass easily; metallic lustre; tarnish, copper-red; powder, blackish-gray; brittle; heated on charcoal gives off sulphur fumes; heated with borax gives a blue glass; gravity 5.
Value.—An ore of cobalt, yielding twenty per cent.
Localities.—Usually found in slate or granite rocks with Copper Pyrites. Mineral Hill, Md. ”

“ Crystals are usually tetrahedral in aspect, owing to the large development of the sphenoid P {111}. The faces of this form are dull and striated, whilst the smaller faces of the complementary sphenoid P′ {111} (fig. 1) {{img float |align=left |width=252px |file=EB1911 Copper Pyrites.jpg |cap= Fig. 1.⁠Fig. 2. are bright and smooth. ”

“ The pyrites cinders from sulphuric acid works afford an abundance of oxide of iron. When the pyrites has contained no copper, the cinders merely require grinding and levigating, the iron being present as oxide. But when the pyriteshas been treated for the recovery of the copper, by a second roasting with salt, the liquors contain the iron as chloride and sulphate, and lime has to be added to precipitate the oxide. ”

“ The sulphurous pyrites are found, some massive, and others crystallized and disseminated in the rock; their colour, of a very clear golden yellow, does not indicate that they contain copper. They are mixed with fibrous sulphuret of iron,* (* Haarkies.) and nodules of swinestone, or fetid carbonate of lime. The marly stratum crosses the torrent; and, as the water washes out metallic grains, the people imagine, on account of the brilliancy of the pyrites, that the torrent bears down gold. ”