Hansesmarkite
Hansesmarkite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Ca₂Mn₂Nb₆O₁₉·20H₂O.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 2–2.5; specific gravity 2.74; Pale yellow streak; Vitreous to resinous luster; optically biaxial.
IMA symbol Hmk, IMA status: approved, named in 2015.
On fracture surfaces in a hydrothermally altered syenite pegmatite dike.
It is found associated with Analcime, arsenopyrite, behoite, bertrandite, calcite, chiavennite, chlorite, epididymite, fluorapophyllite-(K), fluorite, galena, gonnardite, hambergite.
The mineral was named to honor Hans Morten Thrane Esmark (1801-1882), a Norwegian priest from the town of Brevik.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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