Amarillite
Amarillite is an IMA-recognized mineral species in the sulfate class, with the chemical formula NaFe³⁺(SO₄)₂·6H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c). It is a member of the Tamarugite structural group.
Key properties: Mohs hardness 2.5–3; specific gravity 2.19–2.2; Vitreous to adamantine luster; optically biaxial.
IMA symbol Amr, grandfathered status — known before the IMA’s founding, named in 1933.
Formed in the oxidation zones of sulfide deposits.
It is found associated with Coquimbite, other sulfates.
The name is derived from the locality at Tierra Amarilla, Chile.
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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