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Formula: Mn2+3(BO3)2
Anhydrous borate, manganese-bearing
mineral
Crystal System: Orthorhombic
Specific gravity: 3.98 to 4.02 measured, 3.98 calculated
Hardness: 5½
Colour: Pale purplish brown
Common impurities: Mg
Environments
Likely formed by metasomatic reactions between boron-bearing hydrothermal
solutions and rhodochrosite in banded
manganese deposits. Associated minerals include
rhodochrosite, tephroite,
galaxite, jacobsite,
alabandite, galena,
pyrrhotite and chalcopyrite
(HOM).
Localities
At the type locality, the Kaso Mine, Kanuma City, Tochigi Prefecture, Japan, jimboite occurs in banded
carbonate ores, associated with rhodochrosite,
galaxite, jacobsite,
tephroite, alabandite,
galena, pyrrhotite and
chalcopyrite. It was probably formed by metasomatic reaction of
B2O3 with rhodochrosite
(AM 48.1413-1421).
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