Oldhamite Locality: Lichtenberg Absetzer Mine (dump), Ronneburg U deposit, Gera, Thuringia, Germany Dark grey grains, masses and tiny veins of oldhamite in calcite. Ex Fritz Rüger collection. Field of view 1.5 cm. — Photo: Leon Hupperichs · CC BY-SA 3.0
Oldhamite
A pale-brown calcium sulfide — an accessory mineral of enstatite chondrite meteorites, sensitive to moisture.
Intro adapted from Wikipedia (CC BY-SA).
Oldhamite is an IMA-recognized mineral species in the sulfide class, with the chemical formula CaS.
It crystallizes in the cubic crystal system (space group Fm3m). It is a member of the Rocksalt structural group.
Key properties: Mohs hardness 4; specific gravity 2.58.
IMA symbol Old, grandfathered status — known before the IMA’s founding, named in 1863.
Due to high melting point of 2450 ° C, an early nebular condensate; may fill the latest interstices between silicates in enstatite chondrite and achondrite meteorites.
It is found associated with Enstatite, augite, niningerite, osbornite, gypsum, calcite, troilite.
The mineral was named to honor Thomas Oldham (1816–1878), Irish geologist, Director of the Indian Geological Survey (1850–1876).