Galena
PbS [Chemical composition] The composition often contains Ag, Cu, Zn, Tl, As, Bi, Sb, Se, etc., among which Ag is the most important; Se is replaced by the isomorphism of S; there is a complete series of PbS-PbSe homology . [crystal structure] equiaxed crystal system; -Fm3m; a0 = 0.593 nm; Z = 4. The crystal structure is NaCl type: vertical aspect lattice (Fig. L-1), S2-cube is most closely packed, and Pb2+ is filled in all octahedral voids, and the coordination number of anion and cation is 6. Chemically bond to metal ions key transition. FIG. L-1 crystal structure of galena [Forms] are most often in the cube {100}, and octahedron {111}, rhombohedron {110} can also appear, and sometimes appear as octahedrons and cubes. Granulated, dense block aggregates are also common. Figure L-2 galena crystals are in the form of octahedron {111} and cube {100} [Physical properties] lead gray; streaks grayish black; metallic luster. The cleavage parallel {100} is complete; the subspecies containing Bi, see the parallel {111} split. Hardness 2 to 3. The relative density is 74 to 76. With weak conductivity, the crystal has good detection. Causes of occurrence and [] are formed mainly in the warm liquid deposits, lead and zinc sulphide deposits often form together with the sphalerite. Galena can also be formed in the contact metasomatic deposit. Galena is unstable in the oxidation zone and is easily converted into a series of secondary minerals such as lead vanadium and white lead ore. [Identification features] lead gray, strong metallic luster, complete cleavage of the cube, relatively high density, low hardness. [Main use] is the main ore mineral of lead; and Ag-containing galena is an important mineral raw material for refining silver . The crystal can also be used as a detector. Hexagonal Wire Mesh,Twisted Hexagonal Net,Ceiling Decoration Net,Galvanized Square Woven Wire Mesh tengyuan wire mesh , https://www.tengyuansiwang.com