Arsmirandite
Arsmirandite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Na₁₈Cu₁₂Fe³⁺O₈(AsO₄)₈Cl₅.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Arsmirandite structural group.
Key properties: specific gravity 3.715; Grayish green with olive hue streak; Strong vitreous luster.
IMA symbol Asm, IMA status: approved, named in 2014.
Forms as a sublimate around an active volcanic fumarole.
It is found associated with Lehmannite, hematite, sanidine, sylvite, halite, tenorite, cassiterite, rutile, and 40 other species.
The prefix, ars, identifies essential arsenic and mirandus (Latin for ‘marvellous’) in allusion to the unusual crystal structure.
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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