White crystal aggregates of the very rare magnesium sulphate mineral cranswickite (IMA 2010-016) from the type locality and only one of the two known localities worldwide: Calingasta, San Juan, Argentina. — Photo: David Hospital · CC BY-SA 4.0
Cranswickite
Cranswickite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Mg(SO₄)·4H₂O.
It crystallizes in the monoclinic crystal system (space group Cc).
Key properties: specific gravity 1.917.
IMA symbol Cwk, IMA status: approved, named in 2010.
Found in veins of up to 3 cm in thickness in a fine-grained metasedimetary rock (illite, quartz, and gypsum).
It is found associated with Hexahydrite, starkeyite, kieserite.
The mineral was named to honor Lachlan M.D. Cranswick (1968-2010), an Australian crystallographer who helped to develop and maintain the Collaborative Computational Project No.