Rhabdoborite-(W)

rhabdoborite-(W)

rhabdoborite-(V)

rhabdoborite-(Mo)

schaferite

Images

Formula: Mg12W6+1.33O6(BO3)6F2
Borate, rhabdoborite group, the three rhabdoborite group members constitute a series
Crystal System: Hexagonal
Specific gravity: 3.59 calculated
Streak: White
Colour: Light yellow, beige
Environments

Fumeroles

Rhabdoborite is a relatively new mineral, approved in 2018 and to date (September 2023) reported only from the type locality.

Localities

At the type locality, the Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia, three new borate minerals, rhabdoborite-(V), rhabdoborite-(Mo) and rhabdoborite-(W) were found. They are closely associated with each other and with anhydrite, diopside, hematite, schäferite, berzeliite, svabite, calciojohillerite, ludwigite, forsterite, magnesioferrite, baryte, fluorapatite, udinaite, arsenudinaite and powellite. Rhabdoborites form long-prismatic to acicular crystals up to 0.04 × 0.04 × 7 mm3 typically combined in aggregates up to 1 cm. They are transparent, light yellow, and with a vitreous lustre (Physics and Chemistry of Minerals 47.44).
They occur in the fumarole, at a depth of 3 to 4 m below the surface, and at a temperature of 470 to 480°C (Mindat).

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