Esperanzaite
Esperanzaite is an IMA-recognized mineral species in the arsenate class, with the chemical formula NaCa₂Al₂(AsO₄)₂F₄(OH)·2H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/m).
Key properties: Mohs hardness 4.5; specific gravity 3.24; White streak; Vitreous luster; optically biaxial.
IMA symbol Epz, IMA status: approved, named in 1998.
Very rare from a tin-bearing rhyolite.
It is found associated with Hematite, cassiterite, quartz, tridymite, cristobalite, “opal”, calcite, zeolites, mimetite, clay minerals.
The name refers to the La Esperanza mine, Mexico, from which the mineral was collected.
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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