Kegelite

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

Kegelite
Kegelite microcrystals with a 1 cm. siderite crystal at right, from the type locality
General
CategoryPhyllosilicates
Formula
(repeating unit)		Pb8Al4Si8O20(SO4)2(CO3)4(OH)8
Strunz classification9.EC.80
Dana classification71.05.01.01
Crystal systemMonoclinic
Unknown space group
Identification
ColorColorless to white
Crystal habitPseudohexagonal plates in spherical aggregates
CleavagePerfect on {100}
TenacityExtremely flexible
Mohs scale hardnessno data
LusterVitreous
StreakWhite
DiaphaneityTransparent to translucent
Specific gravity4.5
Optical propertiesBiaxial (-)
Refractive indexn = 1.81 parallel to {100}
References[1][2][3]

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


This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.