Kutnohorite , Aragonite Locality: Levane, Bucine , Valdarno (Val d'Arno) , Arezzo Province , Tuscany , Italy (View1.5cm) Two carbonate geode halves lined with tan, radial clusters covered with sparkly and transparent aragonite needles and richly dusted with lustrous, brown botryoidal kutnohorite. These fine pieces are from the well-known lignite mines of Levane, Tuscany, Italy. The locality was featured in a 1994 Mineralogical Record article. — Photo: Didier Descouens · CC BY-SA 4.0
Kutnohorite
A rare calcium-manganese carbonate of the dolomite group, in solid solution with dolomite and ankerite.
Intro adapted from Wikipedia (CC BY-SA).
Kutnohorite is an IMA-recognized mineral species in the carbonate class, with the chemical formula CaMn²⁺(CO₃)₂.
It crystallizes in the hexagonal crystal system (space group R-3c). It is a member of the Calcite-Dolomite structural group.
Key properties: Mohs hardness 3.5–4; specific gravity 3.12; optically uniaxial.
IMA symbol Kut, grandfathered status — known before the IMA’s founding, named in 1903.
is typically found in deposits in association with manganiferous sediments.
It is found associated with Rhodochrosite, aragonite, calcite.
The name refers to its first described occurrence at Kutná Hora, Czech Republic [the original label translated as kutnohorite].