Grey metallic inclusions of the extremely rare Na-Cr sulphide mineral caswellsilverite in a polished meteorite from the the type locality in Norton county, Arkansas (Norton County Meteorite, Norton County, Kansas, United States of America). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Caswellsilverite
Caswellsilverite is an IMA-recognized mineral species in the sulfide class, with the chemical formula NaCrS₂.
It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Scacchite structural group.
Key properties: specific gravity 3.21; Metallic luster.
IMA symbol Cws, IMA status: approved, named in 1981.
Occurs as inclusions in enstatite crystals and in the brecciated matrix of a meteorite (Norton County meteorite); between coarse pyroxene grains in chondrules in a meteorite (Qingzhen meteorite).
It is found associated with Enstatite, cronusite, daubréelite, titanoan troilite, ferromagnesian alabandite, oldhamite, kamacite, perryite, schollhornite (Norton County meteorite).
The mineral was named to honor Dr. Caswell Silver (1916–), American geologist associated with the University of New Mexico, Institute of Meteoritics, Albuquerque, New Mexico, USA.