Inderborite Locality: Deposit No. 6, Inder B deposit and salt dome, Atyrau (Gur'yev) , Atyrau Oblysy (Atyrau Oblast') , Kazakhstan ( Locality at mindat.org ) Size: 11.4 x 6.6 x 6.6 cm. This is a museum-sized specimen of this rare borate, featuring thick, blocky, and really large crystals in the display face pocket. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Inderborite
Inderborite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula CaMg[B₃O₃(OH)₅]₂·6H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c).
Key properties: Mohs hardness 3.5; specific gravity 1.93–2; Vitreous luster; optically biaxial.
IMA symbol Ibo, grandfathered status — known before the IMA’s founding, named in 1941.
With other borates in the caprock of a salt diapir (Inder deposit, Kazakhstan); in lacustrine borate deposits (Sarıkaya, Turkey).
It is found associated with Inyoite, colemanite, ulexite, szaibélyite (Inder deposit, Kazakhstan).
The name refers to the locality from which the first specimens were obtained, the Inder deposit, Kazakhstan, and boron, an essential chemical component.