Hilarionite
Hilarionite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Fe³⁺₂(SO₄)(AsO₄)(OH)·6H₂O.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Kaňkite structural group.
Key properties: Mohs hardness 2; specific gravity 2.4; Vitreous to silky luster.
IMA symbol Hrn, IMA status: approved, named in 2011.
Found as a secondary mineral in the oxidized zone of a sulfide-rich (pyrite, sphalerite, chalcopyrite, galena) orebody.
It is found associated with Goethite, gypsum, bukovskyite, jarosite, melanterite, chalcanthite, allophane, azurite, hematite, unidentified hydrous copper sulfates.
The name refers to the mine that yielded the first specimens.
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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