Galena

Galena is a lead sulfide mineral with a chemical composition of PbS. It is the world's primary ore of lead and is mined from a large number of deposits in many countries. It is found in igneous and metamorphic rocks in medium- to low-temperature hydrothermal veins. In sedimentary rocks it occurs as veins, breccia cements, isolated grains, and as replacements of limestone and dolostone.

Galena is very easy to identify. Freshly broken pieces exhibit perfect cleavage in three directions that intersect at 90 degrees. It has a distinct silver color and a bright metallic luster. Galena tarnishes to a dull gray. Because lead is a primary element in galena, the mineral has a high specific gravity (7.4 to 7.6) that is immediately noticed when picking up even small pieces. Galena is soft with a Mohs hardness of 2.5+ and produces a gray to black streak. Crystals are common and they usually are cubes, octahedrons, or modifications.

Galena

Physical Properties


Physical Properties of Galena

Chemical Classification Sulfide
Color Fresh surfaces are bright silver in color with a bright metallic luster, tarnishes to a dull lead gray
Streak Lead gray to black
Luster Metallic on fresh surfaces, tarnishes dull
Diaphaneity Opaque
Cleavage Perfect, cubic, three directions at right angles
Mohs Hardness 2.5+
Specific Gravity 7.4 to 7.6
Diagnostic Properties Color, luster, specific gravity, streak, cleavage, cubic or octahedral crystals.
Chemical Composition Lead sulfide, PbS
Crystal System Isometric
Uses An ore of lead


Uses of Galena

Galena is a very important mineral because it serves as an ore for most of the world's lead production. It is also a significant ore of silver. Galena has very few uses beyond its service as an ore, but that should not diminish its importance to society.

The number one use of lead today is in the lead-acid batteries that are used to start automobiles. The typical auto battery contains about twenty pounds of lead and must be replaced every four or five years. There are billions of these batteries in the United States alone. Lead-acid batteries are also used as standby power supplies for computer networks, communication facilities, and other critical systems. Lead is also one of the metals used in energy storage systems associated with power generation and hybrid vehicles.


Sources: Geology.com

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