Arangasite
Arangasite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Al₂(SO₄)(PO₄)F·9H₂O.
It crystallizes in the monoclinic crystal system (space group P2/a).
Key properties: Mohs hardness 1–2; specific gravity 2.01; White streak; Dull to silky luster; optically biaxial.
IMA symbol Ans, IMA status: approved, named in 2012.
Found in cavities in quartz–muscovite–tourmaline–sulfide veins and adjacent rock, as a secondary mineral from near-surface oxidation and weathering of a strongly greisenized Li–F two-mica.
It is found associated with Phosphorscorodite, fluellite, gypsum, colquiriite, strengite, mansfieldite, sinkankasite.
The name refers to Arangas Creek, located near the site from which the first specimens were collected.