Chongite
Chongite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Ca₃Mg₂(AsO₄)₂(AsO₃OH)₂·4H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c). It is a member of the Hureaulite structural group.
Key properties: Mohs hardness 3.5; specific gravity 3.09; White streak; Vitreous luster; optically biaxial.
IMA symbol Cng, IMA status: approved, named in 2015.
A secondary mineral from the oxidation of native arsenic and other As -bearing primary phases, followed by later alteration by saline fluids derived from evaporating meteoric water under hyperarid conditions.
It is found associated with Native arsenic, arsenolite, gajardoite, talmessite, torrecillasite.
The mineral was named to honor Dr. Guillermo Chong Díaz (b. 1936), a prominent Chilean geologist and academician.