Vonsenite

minerals

ludwigite

szaibelyite

pyrrhotite

Formula: Fe²⁺₂Fe³⁺O₂(BO₃)
Anhydrous borate, ludwigite group, and forms a series with it
Specific gravity: 4.7
Hardness: 5
Streak: Black, blackish green
Colour: Black, greenish black
Solubility: Slowly soluble in acids
Common impurities: Mg,Al
Environments

Metamorphic environments

Vonsenite is an uncommon high-temperature mineral occurring in contact metamorphic deposits (Mindat), where it occurs in boron-rich skarn associated with magnetite, pyroxene and pyrrhotite (HOM, Webmin).

Localities

The type locality is the Old City Quarry, Riverside, Riverside county, California, USA.

At the Jayville magnetite deposit, At Lawrence county, New York, USA, vonsenite occurs in skarn. Major associates are biotite, clinoamphiboles, Fe-rich diopside and hypersthene. Minor associates include quartz, fluorite, zircon, chlorite, ferroan talc, hematite, pyrite, chalcopyrite and goethite (AM 46.786-811 ).

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