Bornhardtite
Bornhardtite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Co²⁺Co³⁺₂Se₄.
It crystallizes in the cubic crystal system. It is a member of the Spinel structural group.
Key properties: Mohs hardness 4; specific gravity 6.166.
IMA symbol Bhd, grandfathered status — known before the IMA’s founding, named in 1955.
Hydrothermal in origin.
It is found associated with Trogtalite, hastite, clausthalite.
The mineral was named to honor Dr. Wilhelm Bornhardt (1864–1946), German student of ore deposits.
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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