Kegelite

Kegelite

Kegelite microcrystals with a 1 cm. siderite crystal at right, from the type locality
General
Category Silicate mineral
Formula
(repeating unit)		 Pb8Al4Si8O20(SO4)2(CO3)4(OH)8
Strunz classification 09.EC.80 Phyllosilicates
Dana classification 71.05.01.01
Identification
Color Colorless to white
Crystal habit Pseudohexagonal plates in spherical aggregates
Crystal system Monoclinic Space group: A2/m,A2,Am
Cleavage Perfect on {100}
Tenacity Extremely °exible
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. ↑ 1.0 1.1 1.2 http://rruff.geo.arizona.edu/doclib/hom/kegelite.pdf Handbook of Mineralogy
  2. ↑ http://www.webmineral.com/data/Kegelite.shtml Webmineral data
  3. ↑ 3.0 3.1 3.2 http://www.mindat.org/min-2175.html Mindat.org
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