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www.mineralgallery.co.za Minerals F-J |
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Galena |
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Name
Galena
Chemistry
Pbs, Lead Sulfate
Uses
As an ore of lead and as a by-product silver. Also as a popular specimen.
Color
Color is lead to silver gray sometimes with a bluish tint.
Hardness
2.5
Specific gravity
7.5 (Heavy for a metal
Galena, a lead sulfide, PbS, is the most important ore mineral of lead.
Its metallic, lead-gray cubic crystals (isometric system) and cubic, perfectly cleavable masses are distinctive and characteristic. Hardness is 2.5, streak lead gray, and specific gravity 7.4-7.6. Galena is a widespread mineral deposited by hydrothermal solutions as large, irregular masses in dolomitized limestones and in zones of contact metamorphism (see metamorphic rock), and as veins in volcanic rocks. It often contains enough silver to be mined as an ore.
It forms the cubes and octahedron, or combinations of the two. Spinel twinning is possible forming flattened crystals. Also massive and granular. Galena is a common and popular mineral for rock hounds. Its characteristic cubes, distinctive cleavage and high density make it easy to identify and a favorite in high school geology labs.
The structure of Galena is identical to that of halite, NaCl. The two minerals have the same crystal shapes, symmetry and cleavage. Some Galena may contain up to 1% silver in place of lead. The large volume of Galena that is processed for lead produces enough
Silver as a by product to make Galena the leading ore of Silver. The luster is metallic to dull in weathered faces. Cleavage is perfect in four direction forming cubes. Streak is lead gray. Associated minerals are calcite, dolomite, sphalerite, pyrite and other sulfide minerals, also lead oxidation minerals such as cerussite and anglesite.
It has a brighter metallic luster on cleavage surfaces than on crystal faces.
At the Mineral Gallery we take our members on a twice yearly trip to the silver mines at Doornrandjes where you can dig out your own silver galena. See our happenings section for our next trip. Join as a member and receive membership benefits.
