White rounded crystal aggregates of the very rare Mg borate mineral hungchaoite from one of the only three known localities worldwide: Black Hills, Lawrence County, South Dakota, United States of America. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Hungchaoite
Hungchaoite is an IMA-recognized mineral species in the borate class, with the chemical formula MgB₄O₅(OH)₄·7H₂O.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 2–2.5; specific gravity 1.706; Vitreous luster; optically biaxial.
IMA symbol Hch, IMA status: approved, named in 1964.
Found in lacustrine saline borate deposits (China); an efflorescence on weathered colemanite and priceite veins (Death Valley, California, USA).
It is found associated with Ulexite, hydroboracite, szaibélyite, gypsum (China); ginorite, mcallisterite, sborgite, sassolite, nobleite, ulexite, gypsum, kurnakovite, inderite.
The mineral was named to honor Professor Chang Hung-chao (1877–1951), Chinese geologist and mineralogist.