Kegelite , Siderite Locality: Tsumeb Mine (Tsumcorp Mine), Tsumeb , Otjikoto (Oshikoto) Region, Namibia ( Locality at mindat.org ) Size: 2.7 x 2.7 x 2.2 cm. This is a fine thumbnail specimen of kegelite. The somewhat gemmy brown-red crystal in the middle is a remarkably sharp and lustrous siderite. It’s a nice accent to the rolling carpet of extremely rich, microcrystalline kegelite. Ex. Walter Kahn and Eric Asselborn Collections. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Kegelite
A complex lead aluminosilicate with sulfate and carbonate, described in 1975 from Tsumeb and named for mine director Friedrich Kegel.
Intro adapted from Wikipedia (CC BY-SA).
Kegelite is an IMA-recognized mineral species in the silicate class, with the chemical formula Pb₄Al₂Si₄O₁₀(SO₄)(CO₃)₂(OH)₄.
It crystallizes in the monoclinic crystal system.
Key properties: specific gravity 4.5; Vitreous luster; optically biaxial.
IMA symbol Keg, IMA status: approved, named in 1974.
Found in a deep oxidation zone in a polymetallic mineral deposit.
It is found associated with Quartz, galena, mimetite, hematite, leadhillite, anglesite, fleischerite, melanotekite, alamosite.
The name refers to Friedrich Wilhelm Kegel (?{1948), Director of mining operations (1922–1938) at Tsumeb, Namibia.