Nagashimalite

nagashimalite

suzukiite

roscoelite

digenite

Images

Formula: Ba4(V3+,Ti)4(O,OH)2[B2Si8O27]Cl
Cyclosilicate (ring silicate), barium-, vanadium-, titanium- and boron- bearing mineral
Crystal System: Orthorhombic
Specific gravity: 4.08 measured, 4.14 calculated
Hardness: 6
Streak: Green
Colour: Greenish black
Common impurities: Mn,H2O
Environments

Sedimentary environments
Hydrothermal environments

Localities

At the type locality, the Mogurazawa mine, Kiryu City, Gunma Prefecture, Japan, nagashimalite occurs as crystals up to 15 mm long in fissures cutting massive rhodonite ore in bedded chert. Associated minerals include rhodochrosite, rhodonite, suzukiite, baryte, barium-bearing roscoelite, alabandite, digenite, bornite, and tetrahedrite (HOM, Mindat).
Nagashimalite from the Mogurazawa mine - Image

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