Argentiferous galena
| Galena (lead glance) | |
|---|---|
Galena close-up
|
|
| General | |
| Category | Sulfide mineral, octahedral subgroup |
|
Formula (repeating unit) |
PbS |
| Strunz classification | 2.CD.10 |
| Dana classification | 2.8.1.1 |
| Crystal system | Cubic |
| Crystal class | Hexoctahedral (m3m) H–M symbol: (4/m 3 2/m) |
| Space group | Fm3m |
| Unit cell | a = 5.936 Å; Z = 4 |
| Identification | |
| Color | Lead gray and silvery |
| Crystal habit | Cubes and octahedra, blocky, tabular and sometimes skeletal crystals |
| Twinning | Contact, penetration and lamellar |
| Cleavage | Cubic perfect on [001], parting on [111] |
| Fracture | Subconchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 2.5–2.75 |
| Luster | Metallic on cleavage planes |
| Streak | Lead gray |
| Diaphaneity | Opaque |
| Specific gravity | 7.2–7.6 |
| Optical properties | Isotropic and opaque |
| Fusibility | 2 |
| Other characteristics | Natural semiconductor |
| References | |
Galena, also called lead glance, is the natural mineral form of lead(II) sulfide. It is the most important ore of lead and an important source of silver.
Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms. It is often associated with the minerals sphalerite, calcite and fluorite.
Galena is the main ore of lead, used since ancient times. Because of its somewhat low melting point, it was easy to liberate by smelting.
In some deposits galena contains about 1–2% silver, a byproduct that far outweighs the main lead ore in revenue. Galena deposits often also contain significant amounts of silver as included silver sulfide mineral phases or as limited solid solution within the galena structure. These argentiferous galenas have long been the most important ore of silver.
Galena deposits are found worldwide in various environments. Noted deposits include those at Freiberg in Saxony;Cornwall, the Mendips in Somerset, Derbyshire, and Cumberland in England; the Madan, Rhodope Mountains in Bulgaria; the Sullivan Mine of British Columbia; Broken Hill and Mount Isa in Australia; and the ancient mines of Sardinia. Galena also occurs in North African countries and at Mount Hermon in Northern Israel. In the United States, it occurs most notably in the Mississippi Valley type deposits of the Lead Belt in southeastern Missouri, and in the Driftless Area of Illinois, Iowa and Wisconsin. The economic importance of galena to the early history of the Driftless Area was so great that one of the towns in the region was named Galena, Illinois.
...
Wikipedia