White crystals of the rare borate mineral uralborite from the type locality for the mineral (Novofrolovskoye B-Cu Deposit, Turjinsk, Urals Region, Russian Federation) and only one of the two known mineral localities worldwide. — Photo: David Hospital · CC BY-SA 4.0
Uralborite
Uralborite is an IMA-recognized mineral species in the borate class, with the chemical formula CaB₂O₂(OH)₄.
It crystallizes in the monoclinic crystal system (space group P2_1/n).
Key properties: Mohs hardness 4–4.5; specific gravity 2.58–2.6; Vitreous luster; optically biaxial.
IMA symbol Ubo, IMA status: approved, named in 1961.
Found as a rare secondary mineral in boron-rich iron-ore skarns (Novofrolovskoye deposit, Russia); in a vein cutting limestone (Fuka, Japan).
It is found associated with Andradite–grossular, magnetite, szaibélyite, frolovite (Novofrolovskoye deposit, Russia); sibirskite, borcarite, fluorite, calcite (Fuka, Japan).
The name refers to the original locality in the URAL Mountains, Russia, and BORate in its composition.