Galena, Galenite Composition, Crystallization and Structure
Composition. Lead sulphide, PbS = Sulfur 13.4 lead 86.6. Almost always carries traces of silver sulphide, frequently enough to make it a valuable silver ore. At times also contains small amounts of selenium, zinc, cadmium, antimony, bismuth and copper.
Crystallization. Isometric. Most common form is the cube, octahedron sometimes as truncations to cube, more rarely as the simple form 8Fig. 220, 221 and 222; see also A, pl.V). Dodecahedron and trisoctahedron rare.
Structure. Commonly crystallized or massive cleavable; coarse or fine granular.
Physical Properties. Perfect cubic cleavage. H. = 2.5 – 2.75. G. = 7.4 – 7.6. Bright metallic luster. Color and streak lead-gray.
Test. Easily fusible at 2. Reduced on charcoal to lead globule with formation of yellow to white coating of lead oxide. When heated rapidly in the O.F. the coating is heavier and consists chiefly of a white volatile combination of oxides of lead and sulfur, which resembles the antimony oxide coating. Odor of sulfur dioxide when roasted on charcoal or in O.T. When treated with strong nitric acid is oxidized to white lead sulphate. Determined chiefly by its high specific gravity, softness, black streak and cubic cleavage.
Alteration. By oxidation it is converted into the sulphate, anglesite, the carbonate, cerussite, or other compounds.
Occurrence. A very common metallic sulphide, associated with sphalerite, pyrite, marcasite, chalcopyrite, cerussite, anglesite, dolomite, calcite, quartz, barite, fluorite, etc. The veins are commonly in igneous rocks or show a close connection with such rocks. Frequently found with silver mineral, often containing that metal itself and so becoming an important silver ore. A large part of the supply of lead comes as a secondary production from ores mined chiefly for their silver. Occurs most commonly in connection with limestones, either as veins or irregular deposits, or as replacement deposits. The replacement deposits in limestone are commonly accompanied by a dolomitization of the rock and may or may not be associated with igneous rocks. Galena is also found in contact metamorphic deposits.
The following are there important lead producing localities in the United States: Southeastern Missouri, in which the ore occurs in the form of beds with the mineral disseminated through the limestones; southwestern Missouri, where it is associated with zinc ores, and similarly but in smaller amount in Illinois., Iowa, and Wisconsin. From Idaho, where the lead is derived chiefly form lead-silver deposits, the greater part of which come from near Wallace in Shoshone County; Utah, in connection with the silver deposits of the Tintic and Park City districts; Colorado, chiefly from the lead-silver ores of the Leadville District.
The most famous foreign localities are, Freiberg, Saxony; the Harz Mountains; from Westphalia and Nassau; Pribram, Bohemia in Czechoslovakia; Cornwall, Derbyshire and Cumberland, England.
Name. The name galena is derived from the Latin galena a name originally given to lead ore..
Use. Practically the only source of lead and important ore of silver. Metallic lead is used chiefly as follows: for conversion into white lead (a basic lead carbonate), which is the principal ingredient of the best white paints, or into the oxides used in making glass and in giving a glaze to earthenware; as pipe and sheets; for shot; it is one of the ingredients of solder (an alloy of lead and tin), of type metal (an alloy of lead and antimony) and of low fusion alloys consisting of lead, bismuth and tin.
The following rare tellurides belong in this group; hessite, Ag2Te; petzite (Ag, Au)2 Te; altaite, PbTe.
What is a Hammermill used for? Applications Before Mining Begins Underground Drilling Use of Plaster of Paris Tablets MINING OPERATION and Metallurgy of POLYMETALLIC DEPOSIT WITH PRECIOUS METALS Peripheral Speeds Hydrometallurgy Identifying Manganese Minerals Aluminum Elements, Alloys and Symbols Geological Risks Galena coexisting VS bismuth and copper content Sampling a Ore Deposit Titanite, Sphene Composition, Crystallization & Structure Pegmatite Dikes and Veins Datolite Composition, Crystallization & Structure
