Galena

For other uses, see Galena (disambiguation).

Galena
General
Category	Sulfides
Chemical formula	lead sulfide (PbS)
Identification
Color	Lead gray, silvery
Crystal habit	Cubes and octahedra, tabular and sometimes skeletal crystals
Crystal system	Isometric hexoctahedral
Cleavage	Cubic
Fracture	Flat (when cubic) to even
Mohs Scale hardness	2.5 - 2.75
Luster	Metallic
Refractive index	Opaque
Pleochroism	None
Streak	Lead gray
Specific gravity	7.4 - 7.6
Fusibility	2

Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.

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.

Lead ore deposits

Galena deposits often 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 in mining. In addition zinc, cadmium, antimony, arsenic and bismuth also occur in variable amounts in lead ores. Selenium substitutes for sulfur in the structure constituting a solid solution series. The lead telluride mineral altaite has the same crystal structure as galena. Within the weathering or oxidation zone galena alters to anglesite (lead sulfate) or cerussite (lead carbonate).

File:Galena Poland.jpg

Galena from Poland

Galena deposits are found in France, Romania, Austria, Belgium, Italy, Spain, Scotland, England, Australia, and Mexico. Noted deposits include those at Freiberg, Saxony; Cornwall, Derbyshire, and Cumberland, England; the Sullivan mine of British Columbia; and Broken Hill, Australia. Galena also occurs 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 similar environments in Illinois, Iowa and Wisconsin. Galena also was a major mineral of the zinc-lead mines of the tri-state district arpond Joplin in southwestern Missouri and the adjoining areas of Kansas and Oklahoma. Galena is also an important ore mineral in the silver mining regions of Colorado, Idaho, Utah and Montana. Of the latter, the Coeur d'Alene district of northern Idaho was most prominent.

Galena is the official state mineral of the U. S. states: Missouri and Wisconsin.

Uses

File:Fluorite galena09.jpg

Dark gray cubes of galena with fluorite (purple) and calcite (white) from Illinois, USA

One of the earliest uses of galena was as kohl, which in Ancient Egypt was applied around the eyes to reduce the glare of the desert sun and to repel flies, a potential source of disease.

Galena is a semiconductor with a small bandgap of 0.4 eV. In the early days of wireless, it was used as the semiconductor (i.e. the crystal) in crystal radio sets; combined with a safety pin or similar sharp wire (known as a "cat's whisker"), the galena crystal became part of a point-contact diode used to detect radio signals. Scientists linked to this application were Karl Ferdinand Braun and Sir Jagdish Bose.

See also

• List of minerals

References

ISBN links support NWE through referral fees

• Klein, Cornelis and Cornelius S. Hurlbut, Jr. (1985) Manual of Mineralogy, Wiley, 2nd ed., pp. 274-276, ISBN 0-471-80580-7
• Webmineral data
• Mindat with location data
• Franklin and Sterling Hill mineral deposits
• Mineral Data Publishing - PDF

External links

• Case Studies in Environmental Medicine (CSEM): Lead Toxicity
• ToxFAQs™: Lead
• Mineral information institute entry for lead

ca:Galena cs:Galenit de:Galenit et:Galeniit es:Galena fr:Galène it:Galena he:גלנה lt:Galenitas nl:Galeniet ja:方鉛鉱 no:Blyglans pl:Galena pt:Galena ru:Галенит simple:Galena sk:Galenit fi:Lyijyhohde sv:Blyglans zh:方铅矿