Kegelite: Properties and Occurrences

Kegelite is a complex silicate mineral with formula Pb8Al4Si8O20(SO4)2(CO3)4(OH)8. It is a monoclinic mineral containing aluminum, carbon, hydrogen, lead, oxygen, silicon, and sulfur. It was first described in 1975 for an occurrence in the Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia and named for Friedrich Wilhelm Kegel (?-1948), Director of mining operations at Tsumeb.

General Information

  • Category: Phyllosilicates
  • Formula: Pb8Al4Si8O20(SO4)2(CO3)4(OH)8
  • Crystal system: Monoclinic
  • Unknown space group

Fig: Kegelite


  • Color: Colorless to white
  • Crystal habit: Pseudohexagonal plates in spherical aggregates
  • Cleavage: Perfect on {100}
  • Tenacity: Extremely flexible
  • Mohs scale hardness: no data
  • Luster: Vitreous
  • Streak: White
  • Diaphaneity: Transparent to translucent
  • Specific gravity: 4.5

Occurrence: In a deep oxidation zone in a polymetallic mineral deposit. It occurs in deeply oxidized polymetallic ore deposits in Tsumeb. It has also been reported from the Zeehan district in Tasmania and from Tune, Sharpsburg, Østfold, Norway.

Association: Quartz, galena, mimetite, hematite, leadhillite, anglesite, eischerite, melanotekite, alamosite.


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