Yellowish crystals of the extremely rare mineral feinglosite associated to also yellowish helmutwinklerite, both minerals typical of Tsumeb, but in this case from Vouves, Thasos Island, Macedonia Department, Greece. Both in a matrix of massive adamine. Specimen analyzed by SEM/EDS. — Photo: David Hospital · CC BY-SA 4.0
Feinglosite
Feinglosite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Pb₂Zn(AsO₄)₂·H₂O.
It crystallizes in the monoclinic crystal system. It is a member of the Brackebuschite structural group.
Key properties: Mohs hardness 4–5; specific gravity 6.56; White streak; Adamantine luster.
IMA symbol Fgl, IMA status: approved, named in 1995.
A very rare secondary mineral, in a cavity in chalcocite, from an oxidized zone in a dolostone-hosted hydrothermal polymetallic ore deposit.
It is found associated with Goethite, anglesite, wulfenite, chalcocite, arsendescloizite, gypsum.
The mineral was named to honor Dr. Mark N. Feinglos (1948–), American medical researcher and mineral collector specializing in Tsumeb minerals, Durham, North Carolina, USA.