Alamosite , Leadhillite , Melanotekite Locality: Tsumeb , Otjikoto (Oshikoto) Region, Namibia ( Locality at mindat.org ) Size: miniature, 3.5 x 2.5 x 1.5 cm Alamosite, Melanotekite, Leadhillite A small piece but truly oustanding for the finely crystallized alamosite on matrix of finely crysatllized leadhillite, and for the richeness and near-record size of the melanotekite! The overall combination is a relative value in that you get three very rare minerals, in excellent crystals, altogether - and in a displayable specimen, no less! — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Alamosite
A colorless lead silicate from Álamos, Mexico — a rare secondary mineral in the oxidized zone of lead deposits.
Intro adapted from Wikipedia (CC BY-SA).
Alamosite is an IMA-recognized mineral species in the silicate class, with the chemical formula PbSiO₃.
It crystallizes in the monoclinic crystal system (space group P2/n).
Key properties: Mohs hardness 4.5; specific gravity 6.488; Adamantine luster; refractive index 1.959; optically biaxial.
IMA symbol Aam, grandfathered status — known before the IMA’s founding, named in 1909.
A rare secondary mineral found in the oxidized zone of lead-bearing base metal deposits.
It is found associated with Wulfenite, leadhillite, cerussite (Alamos, Mexico); leadhillite, anglesite, melanotekite, fleischerite, kegelite, hematite (Tsumeb, Namibia); diaboleite.
The name refers to the Mexican type locality at Alamos.