Boldut Mine, Cavnic, Maramureș, Romania

MnCO₃

Crystal System: trigonal
Colour: pink, rose, red, yellowish-grey, brown, white, gray
Lustre: vitreous, pearly
Habitus: rare rhomboedral, scalenohedral. Common concretion, mammillary, stalactite
Hardness: 3½ - 4
Fracture: irregular/uneven, conchoidal
Cleavage: perfect on {10-11}
Density: 3.70 g/cm³ 
Origin and geological occurrence: it occurs as a primary gangue mineral in hydrothermal low- to moderate T veins. It can also be found in metamorphic environments (often in metamorphosed Mn deposits).

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Samples: 

5.17 Rhodochrosite cleaved masses of rhodochrosite. Saguache County, Colorado, USA #carbonates