Brianroulstonite
Brianroulstonite is an IMA-recognized mineral species in the borate class, with the chemical formula Ca₃B₅O₆(OH)₇Cl₂·8H₂O.
It crystallizes in the monoclinic crystal system (space group Pa). It is a member of the Brianroulstonite structural group.
Key properties: Mohs hardness 5; specific gravity 1.97; White streak; Vitreous luster; optically biaxial.
IMA symbol Brsn, IMA status: approved, named in 1996.
Very rare in residues from halite–sylvite evaporites.
It is found associated with Halite, hilgardite, pringleite, trembathite, sellaite, fluorite, hematite, muscovite, penobsquisite, “clay”.
The mineral was named to honor Brian V. Roulston (1948–), geologist and specialist in evaporite deposits.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
Browse more B minerals or help write this entry.