Chemical Formula for Galena

Bond

• Sulfides are covalently bonded, meaning that each lead atom and each sulphur atom in galena share a pair of electrons. However, as with many sulfides, the metal atoms in galena are not completely isolated by their sulphur bond. Some metal to metal bonding occurs. Metallic bonding is tightly packed, so that electrons of the outer orbit are "delocalized," meaning that they move among the orbits of many atoms. Light reflects from the free electrons in the metal to metal bonds, giving galena a metallic shine.

Crystals

• Delocalized electrons make metals malleable, able to be shaped without breaking. The metal to sulphur bonds in galena determine its brittle cleavage. Galena usually occurs in an isometric (cubic) form, the simplest mineral crystal, or sometimes as an octahedron. When galena is cleaved, the isometric cleavage on three distinct planes is preserved down to the smallest size. Galena minerals were the self-powered "crystals" in crystal sets, the earliest radios. The sets recovered radio waves and acted as a diode to convert frequency to weak audio power.

Silver

• The mineral galena can include other metals along with the lead. In argentiferous galena, silver (Ag) atoms substitute for some of the lead (Pb) atoms. In another argentiferous galena, matildite, a silvery-bismuth sulfide (AgBi)S2, the substitution is more complex, with a combination of one silver and one bismuth (Bi) replacing two lead atoms. Matildite was first identified in 1883 among galena at Matilda Mine in Peru. Galena can also include antimony (Sb) along with silver as miargyrite, a silver-antimony sulfide, (AgSb)S2. Miargyrite was first identified in 1824 among galena at Neue Hoffnung Gottes Mine, Saxony (now in Germany).

Anglesite

• Anglesite (PbSO4) was named after the lead mines at Anglesey, Wales. Anglesite is a secondary mineral that forms when the lead sulfide in galena oxidizes in hydrothermal veins. Some or all of the mineral becomes a sulfate (SO4) rather than a sulfide (S). Anglesite has a very brittle fracture, resulting in conchoid fragmentation, a fracture along no defined plane of crystal structure. Anglesite is 68.3 percent lead, 10.57 percent sulphur, and 21.1 percent oxygen.

Cerussite

• Cerussite is lead carbonate, Pb(CO3), a mineral formed when carbon dioxide in water interacts with anglesite. Cerussite is sometimes found as a granular powder on the surface of galena. It includes traces of silicon, iron and clay impurities from groundwater. Cerussite is brittle, fractures conchoidally into fragments, and shatters when heated. Cerussite was the "white lead" anciently used in cosmetics and paint, but industrial production of lead paint was accomplished by adding sodium bicarbonate to a lead salt. Cerusite is 16.5 percent carbon dioxide and 83.5 percent lead oxide (77.5 percent lead).

Detailed references that you can delete after the edit.

• Info for the overview is from The Mineral Galena,
  http://www.minerals.net/mineral/sulfides/galena/galena.htm
  AND
  from Mineral Information Institute, http://www.mii.org/Minerals/photolead.html

  All info for Section 1 is from Rocks and Minerals: A Guide to Field Identification By Charles A. Sorrell, George F. Sandström, page 26. http://books.google.com/books?id=7a8cQuKTWeUC&pg=PA26&lpg=PA26&dq

  The second sentence of Section 2 is from Rocks and Minerals, op. cit.
  AND
  the remainder of Section 2 is from Crystallography and Practical Crystal Measurement, Alfred Edwin Howard Tutton, 1922, page 527 http://books.google.com/books?id=MCwLAQAAIAAJ&pg=PA527&dq
  EXCEPT
  the last two sentences, which are from Radio-frequency electronics: circuits and applications, Jon B. Hagen, 1996, page 55 http://books.google.com/books?id=QtJ5tNdlyYAC&pg=PA55&lpg=PA55&dq

  Most of Section 3 is from an abstract for A solution model for high-temperature PbS-AgSbS2-AgBiS2 galena, Nathan I. Chutas, American Mineralogist; October; v. 93; no. 10; p. 1630-1640 http://ammin.geoscienceworld.org/cgi/content/abstract/93/10/1630
  AND
  Matilda Mine info from http://www.mindat.org/min-2592.html
  AND
  Neue Hoffnung Gottes Mine info is from http://www.mindat.org/min-2702.html

  Section 4 info is from Anglesite Mineral Data, http://webmineral.com/data/Anglesite.shtml
  http://webmineral.com/data/Anglesite.shtml
  AND
  from http://www.minerals.net/mineral/sulfates/anglesit/anglesit.htm
  AND
  from Rocks and Minerals: A Guide to Field Identification By Charles A. Sorrell, George F. Sandström, 2001, page 240 http://books.google.com/books?id=7a8cQuKTWeUC&pg=PA240&dq

  For Section 5, the information about lead paint is from Practical chemistry, Lyman Churchill Newell, 1922, page 460 http://books.google.com/books?id=4u1EAAAAIAAJ&pg=PA460&dq
  AND
  the brittleness info is from Gems: Their Sources, Descriptions and Identification, Michael O'Donoghue, 1962, page 396-397. http://books.google.com/books?id=ZwcM5H-wHNoC&pg=PA396&dq
  AND
  the remainder is from Bulletin, Issue 9 By Oklahoma Geological Survey, 1912, page 5. http://books.google.com/books?pg=PA5&dq