Outstanding yellow very shiny microcrystals of the rare borate mineral preobrazhenskite from the type locality: Inder B Deposit, Atyrau, Atyrau Oblysy, Kazakhstan. — Photo: David Hospital · CC BY-SA 4.0
Preobrazhenskite
Preobrazhenskite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Mg₃B₁₁O₁₅(OH)₉.
It crystallizes in the orthorhombic crystal system (space group Pbcn).
Key properties: Mohs hardness 4.5–5; specific gravity 2.45; optically biaxial.
IMA symbol Pbz, grandfathered status — known before the IMA’s founding, named in 1956.
Found in fine-grained halite–polyhalite rock.
It is found associated with Inyoite, halite, polyhalite, kieserite, anhydrite, aksaite, boracite, ginorite, halurgite, strontioborite, metaborite, kaliborite.
The mineral was named to honor Pavel Ivanovich Preobrazhenskii (1874–1944), investigator of Russian salt deposits, Institute of Halurgy, St. Petersburg, and Institute of Mining and Chemical Stock.