Kutnohorite
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Kutnohorite is a rare calcium manganese magnesium iron carbonate mineral with formula Ca(Mn,Mg,Fe)(CO3)2. It is a manganese rich analogue of the dolomite-ankerite series. It crystallizes in the trigonal system and occurs as massive to bundled blades of white through rose pink to light brown crystal forms. The pink shades are due to increased manganese whereas the brown colors are due to increased iron content. It shows the perfect three directions of cleavage typical of carbonates. It has a Mohs hardness of 3.5 to 4 and a specific gravity of 3.1 - 3.12. It is translucent to transparent with refractive index values of nω = 1.727 and nε = 1.535.
It was first described in 1901 and named for its type locality of Kutna Hora, Bohemia, Czech Republic.
