Kegelite

Kegelite

Kegelite microcrystals with a 1 cm. siderite crystal at right, from the type locality
General
Category Phyllosilicates
Formula
(repeating unit)		 Pb8Al4Si8O20(SO4)2(CO3)4(OH)8
Strunz classification 9.EC.80
Dana classification 71.05.01.01
Crystal system Monoclinic
Unknown space group
Identification
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
Optical properties Biaxial (-)
Refractive index n = 1.81 parallel to {100}
References [1][2][3]

Kegelite is a complex silicate mineral with formula Pb8Al4Si8O20(SO4)2(CO3)4(OH)8.

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.[1][3] It occurs in a deeply oxidized polymetallic ore deposits in Tsumeb. Associated minerals include quartz, galena, mimetite, hematite, leadhillite, anglesite, fleischerite, melanotekite and alamosite.[1] It has also been reported from the Zeehan district in Tasmania and from Tune, Sarpsberg, Østfold, Norway.[3]

References

  1. 1 2 3 http://rruff.geo.arizona.edu/doclib/hom/kegelite.pdf Handbook of Mineralogy
  2. ↑ http://www.webmineral.com/data/Kegelite.shtml Webmineral data
  3. 1 2 3 http://www.mindat.org/min-2175.html Mindat.org
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