Galena
Lead glance
Galena - Huallanca, Bologesi, Ancash, Peru.jpg
Galena with minor pyrite
General
CategorySulfide mineral, octahedral subgroup
Formula
(repeating unit)
PbS
Strunz classification2.CD.10
Dana classification2.8.1.1
Crystal systemCubic
Crystal classHexoctahedral (m3m)
H–M symbol: (4/m 3 2/m)
Space groupFm3m
Unit cella = 5.936 Å; Z = 4
Identification
ColorLead gray and silvery
Crystal habitCubes and octahedra, blocky, tabular and sometimes skeletal crystals
TwinningContact, penetration and lamellar
CleavageCubic perfect on [001], parting on [111]
FractureSubconchoidal
TenacityBrittle
Mohs scale hardness2.5–2.75
LusterMetallic on cleavage planes
StreakLead gray
DiaphaneityOpaque
Specific gravity7.2–7.6
Optical propertiesIsotropic and opaque
Fusibility2
Other characteristicsNatural semiconductor
References[1][2][3]
The rock-salt crystal structure. Each atom has six nearest neighbors, with octahedral geometry.

Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver.[4]

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 depositsEdit

 
Galena with baryte and pyrite from Cerro de Pasco, Peru; 5.8 cm × 4.8 cm × 4.4 cm (2.3 in × 1.9 in × 1.7 in)

Galena is the main ore of lead, used since ancient times,[5] since lead can be smelted from galena in an ordinary wood fire.[6] Galena typically is found in hydrothermal veins in association with sphalerite, marcasite, chalcopyrite, cerussite, anglesite, dolomite, calcite, quartz, barite, and fluorite. It is also found in association with sphalerite in low-temperature lead-zinc deposits within limestone beds. Minor amounts are found in contact metamorphic zones, in pegmatites, and disseminated in sedimentary rock.[7]

In some deposits the galena contains up to 0.5% silver, a byproduct that far surpasses the main lead ore in revenue. In these deposits significant amounts of silver occur as included silver sulfide mineral phases or as limited silver in solid solution within the galena structure. These argentiferous galenas have long been an important ore of silver.[8][9]Silver-bearing galena is almost entirely of hydrothermal origin; galena in lead-zinc deposits contains little silver.[10]

 
A microscopic picture of Galena

Galena deposits are found worldwide in various environments.[3] Noted deposits include those at Freiberg in Saxony;[1] Cornwall, the Mendips in Somerset, Derbyshire, and Cumberland in England; the Madan and Rhodope Mountains in Bulgaria; the Sullivan Mine of British Columbia; Broken Hill and Mount Isa in Australia; and the ancient mines of Sardinia.

In the United States, it occurs most notably as lead-zinc ore in the Mississippi Valley type deposits of the Lead Belt in southeastern Missouri, which is the largest known deposit,[1] and in the Driftless Area of Illinois, Iowa and Wisconsin. Galena also was a major mineral of the zinc-lead mines of the tri-state district around Joplin in southwestern Missouri and the adjoining areas of Kansas and Oklahoma.[1] 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.[1]

Australia is world's leading producer of lead as of 2021, most of which is extracted as galena. Argentiferous galena was accidentally discovered at Glen Osmond in 1841, and additional deposits were discovered near Broken Hill in 1876 and at Mount Isa in 1923.[11] Most galena in Australia is found in hydrothermal deposits emplaced around 1680 million years ago, which have since been heavily metamorphosed.[12]

The largest documented crystal of galena is composite cubo-octahedra from the Great Laxey Mine, Isle of Man, measuring 25 cm × 25 cm × 25 cm (10 in × 10 in × 10 in).[13]

ImportanceEdit

Galena is the official state mineral of the U.S. states of Kansas,[14] Missouri,[15] and Wisconsin;[16] the former mining communities of Galena, Kansas,[17][18] and Galena, Illinois,[19] take their names from deposits of this mineral.

Crystal structureEdit

Galena belongs to the octahedral sulfide group of minerals that have metal ions in octahedral positions, such as the iron sulfide pyrrhotite and the nickel arsenide niccolite. The galena group is named after its most common member, with other isometric members that include manganese bearing alabandite and niningerite.[20][3]

Divalent lead (Pb) cations and sulfur (S) anions form a close-packed cubic unit cell much like the mineral halite of the halide mineral group. Zinc, cadmium, iron, copper, antimony, arsenic, bismuth and selenium also occur in variable amounts in galena. Selenium substitutes for sulfur in the structure constituting a solid solution series. The lead telluride mineral altaite has the same crystal structure as galena.[21]

GeochemistryEdit

Within the weathering or oxidation zone galena alters to anglesite (lead sulfate) or cerussite (lead carbonate).[22] Galena exposed to acid mine drainage can be oxidized to anglesite by naturally occurring bacteria and archaea, in a process similar to bioleaching.[23]

Uses of galenaEdit

One of the oldest uses of galena was in the eye cosmetic kohl. In Ancient Egypt, this was applied around the eyes to reduce the glare of the desert sun and to repel flies, which were a potential source of disease.[24]

In pre-Columbian North America, galena was used by indigenous peoples as an ingredient in decorative paints and cosmetics, and widely traded throughout the eastern United States.[25] Traces of galena are frequently found at the Mississippian city at Kincaid Mounds in present-day Illinois.[26] The galena used at the site originated from deposits in southeastern and central Missouri and the Upper Mississippi Valley.[25]

Galena is the primary ore of lead, and is often mined for its silver content.[8]

It can be used as a source of lead in ceramic glaze.[27]

 
Galena cat's whisker detector

Galena is a semiconductor with a small band gap of about 0.4 eV, which found use in early wireless communication systems. It was used as the crystal in crystal radio receivers, in which it was used as a point-contact diode capable of rectifying alternating current to detect the radio signals. The galena crystal was used with a sharp wire, known as a "cat's whisker" in contact with it.[28]

See alsoEdit

ReferencesEdit

  1. ^ a b c d e Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (1990). "Galena". Handbook of Mineralogy (PDF). 1. Chantilly, VA: Mineralogical Society of America. ISBN 0962209708.
  2. ^ Galena. Webmineral
  3. ^ a b c Galena. Mindat.org
  4. ^ Young, Courtney A.; Taylor, Patrick R.; Anderson, Corby G. (2008). Hydrometallurgy 2008: Proceedings of the Sixth International Symposium. SME. ISBN 9780873352666.
  5. ^ Lucas, A. (May 1928). "Silver in Ancient Times". The Journal of Egyptian Archaeology. 14 (1): 313–319. doi:10.1177/030751332801400160.
  6. ^ Winder, C. (1993b). "The history of lead — Part 3". LEAD Action News. 2 (3). ISSN 1324-6011. Archived from the original on 31 August 2007. Retrieved 12 February 2016.
  7. ^ Klein, Cornelis; Hurlbut, Cornelius S., Jr. (1993). Manual of mineralogy : (after James D. Dana) (21st ed.). New York: Wiley. pp. 354–356. ISBN 047157452X.
  8. ^ a b Lucas 1928.
  9. ^ Wood, J. R.; Hsu, Y-T.; Bell, C. (2021). "Sending Laurion Back to the Future: Bronze Age Silver and the Source of Confusion". Internet Archaeology. 56.9. doi:10.11141/ia.56.9.
  10. ^ Klein & Hurlbut 1993.
  11. ^ "Lead". Geoscience Australia. Australian Government. Retrieved 26 June 2021.
  12. ^ Walters, Stephen; Bailey, Andrew (1998-12-01). "Geology and mineralization of the Cannington Ag-Pb-Zn deposit; an example of Broken Hill-type mineralization in the eastern succession, Mount Isa Inlier, Australia". Economic Geology. 93 (8): 1307–1329. doi:10.2113/gsecongeo.93.8.1307.
  13. ^ Rickwood, P. C. (1981). "The largest crystals" (PDF). American Mineralogist. 66: 885–907.
  14. ^ "2018 Statute Chapter 73 Article 38", Official state mineral, Kansas Legislature, retrieved 2019-12-05
  15. ^ "Office of the Secretary of State, Missouri – State Symbols". State of Missouri. Retrieved 2009-11-12.
  16. ^ "Wisconsin State Symbols". State of Wisconsin. Archived from the original on 2010-01-12. Retrieved 2009-11-12.
  17. ^ Kansas Place-Names, John Rydjord, University of Oklahoma Press, 1972, p. 77 ISBN 0-8061-0994-7
  18. ^ Gannett, Henry (1905). The Origin of Certain Place Names in the United States. Govt. Print. Off. p. 133.
  19. ^ Galena Historical Society (June 21, 2006). "History Highlights". Retrieved April 13, 2007.
  20. ^ Klein & Hurlbut 1993, pp. 354–355.
  21. ^ Klein & Hurlbut 1993, pp. 354–356.
  22. ^ Klein & Hurlbut 1993, p. 355.
  23. ^ Da Silva, Gabriel (2004). "Kinetics and mechanism of the bacterial and ferric sulphate oxidation of galena". Hydrometallurgy. 75: 99. doi:10.1016/j.hydromet.2004.07.001.
  24. ^ Metropolitan Museum of Art (2005). The Art of Medicine in Ancient Egypt. New York. p. 10. ISBN 1-58839-170-1.
  25. ^ a b "Lead pollution from Native Americans attributed to crushing galena for glitter paint, adornments". Indiana University–Purdue University Indianapolis. 21 October 2019. Retrieved 11 January 2020.
  26. ^ The Glittery Legacy of Lead at a Historic Native American Site, Atlas Obscura, November 7, 2019
  27. ^ Glaze, http://www.thepotteries.org/types/glaze.htm.
  28. ^ Lee, Thomas H. (2007). "The (Pre-)History of the Integrated Circuit: A Random Walk" (PDF). IEEE Solid-State Circuits Newsletter. 12 (2): 16–22. doi:10.1109/N-SSC.2007.4785573. ISSN 1098-4232.[permanent dead link]

Further readingEdit

External linksEdit