Grey massive crystal aggregates of the very rare Mg-Sb mineral bystromite from the type locality in Sonora (La Fortuna Mine, El Antimonio, Caborca Municipality, Sonora, Mexico), and associated to yellow stibiconite. — Photo: David Hospital · CC BY-SA 4.0
Byströmite
Byströmite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula MgSb⁵⁺₂O₆.
It crystallizes in the tetragonal crystal system (space group P4_2/mnm). It is a member of the Tapiolite structural group.
Key properties: Mohs hardness 7; specific gravity 5.5; Pale gray streak.
IMA symbol Bym, grandfathered status — known before the IMA’s founding, named in 1952.
Found in quartz veins in an oxidized antimony deposit.
It is found associated with Stibiconite, quartz.
The name refers to Dr. Anders Byström (1916–1956), Swedish crystal chemist, who made a structural analysis of the synthetic compound.