- This article is about the mineral, for a resident of Tokyo see Edokko.
|Crystal symmetry||Monoclinic 2/m|
|Unit cell||a = 9.104 Å, b = 6.132 Å, c = 7.895 Å β = 112.2°, Z=2|
|Crystal habit||Occurs as splotchy, anhedral crystals forming inclusions|
|Crystal system||Monoclinic - Prismatic|
|Mohs scale hardness||4.5 - 5|
|Streak||Deep brownish red|
|Specific gravity||4.62 calculated|
|Optical properties||Biaxial (?)|
|Refractive index||a=1.99, g=2.03|
|Pleochroism||Distinct, reddish orange to dark brownish red|
Tokyoite is a rare barium manganese vanadate mineral with the chemical formula: Ba2(Mn3+,Fe3+)OH(VO4)2. It is the manganese analogue of the iron rich gamagarite and the barium analogue of the lead vanadate, brackebuschite.
It was first reported for an occurrence in the Shiromaru Mine, Okutama, Tama district, Tokyo Prefecture, Kanto Region, Honshu Island, Japan and approved by the IMA in 2003. It has been found in two mines in Italy and one in Japan, for which it was named.
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