Galena (from lat. Galena - “ lead ore ”, “scale”; obsolete lead shine [1] ) is a mineral from the sulfide class, the most important source of lead. Under the name galena, the mineral is mentioned in the writings of the Roman encyclopedist Pliny the Elder (77 A.D. ) [2] .
| Galena | |
|---|---|
 Galena on quartz | |
| Formula | Pbs |
| Impurity | Ag , Cd , Se |
| Physical properties | |
| Colour | Lead gray |
| Trait color | Gray black |
| Shine | Metal |
| Transparency | Opaque |
| Hardness | 2,5-3 |
| Cleavage | Perfect in {111} |
| Kink | Stepped |
| Density | 7.4-7.6 g / cm³ |
| Syngonia | Cubic |
Content
Composition and properties
According to the chemical composition of galena - lead (II) sulfide (PbS).
Galena often contains impurities of Ag , Cd , Se , etc. Lead-gray crystals and aggregates. Hardness 2-3; density 7.4-7.6 g / cm³. The color is steel, gray with a bluish tint, sometimes there is a mottled tinge, the luster is metallic, the break is stepped, fragile. Cleavage perfect in a cube . It forms cubic, cuboctahedral, less often octahedral crystals and continuous masses. Hydrothermal and metasomatic deposits. Upon contact with air, galena quickly oxidizes , darkens and loses its luster. In the weathering of galena, such minerals of lead as cerussite and anglesite are formed in the deposits [2] . Under hypergenic conditions, it changes with the formation of carbonates (for example, phosgenite ) and lead sulfates. The main ore is lead.
The crystalline structure of galena is of the coordination type.
Forms crystals of cubic syngony , space group Fm 3 m , cell parameters a = 0.5936 nm , Z = 4 .
Sometimes it forms solid solutions with rare isomorphic minerals claustalite ( lead (II) PbSe selenide ) and altaite ( lead (II) PbTe telluride ).
Differences
Galena is easily determined by its characteristic “lead-gray” color and intense “silver” shine, as well as by its high density inherent in this mineral [3] .
Galenite differs from arsenopyrite in color, higher density, low hardness, cleavage in a cube.
Distribution
Galena is one of the most common hydrothermal sulfides. It is often found in the form of dense granular masses of lead-gray color together with sphalerite , pyrite , chalcopyrite , quartz , fluorite , and carbonates .
The United States is the world leader in galena mining, followed by Russia , Australia , Canada and Mexico . In Africa, galena is mined in Morocco and Namibia , but the deposits of these countries are close to depletion. Ancient galena mines in Central and Northern Europe ( Germany , Czech Republic , Great Britain and France ) are practically exhausted. The same can be said about Spain , which at that time occupied a leading position in the production of galena [2] .
Presumably exists on Venus, forming together with bismuth sulfide the surface layer of some elevations [4] .
Literature
- Galenit // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
Notes
- ↑ Klenova M.V. Finding of lead shine in Serebryanka Bay on Novaya Zemlya // Economy of the North. 1931. No. 9/10. S. 162-163.
- ↑ 1 2 3 Galenite // Minerals. Treasures of the Earth: Weekly Edition. - De Agostini, 2011. - No. 35 . - ISSN 2075-0587 .
- ↑ Alyavdin V.F., Betekhtin A.G. Galenit // Minerals of the USSR. T. 2. M .; L .: Publishing House of the Academy of Sciences of the USSR, 1940.
- ↑ Carolyn Jones Otten. 'Heavy metal' snow on Venus is lead sulfide / Washington University in St. Louis. February 10, 2004.