Article · Wikipedia archive · Last revised Jul 5, 2026

Alarsite

Alarsite (AlAsO4) is an aluminium arsenate mineral with its name derived from its composition: aluminium and arsenate. It occurs as brittle subhedral grains which exhibit trigonal symmetry. It has a Mohs hardness of 5-5.5 and a specific gravity of 3.32. It is semitransparent, colorless with pale yellow tints and shows a vitreous luster. It is optically uniaxial (+) with refractive indices of nω = 1.596 and nε = 1.608.

Last revised
Jul 5, 2026
Read time
≈ 1 min
Length
156 w
Citations
5
Source
Alarsite
Alarsite crystals found at Tolbachik
General
CategoryMinerals
IMA symbolArs1
Crystal systemtrigonal
Crystal classaluminium arsenate
Space groupP3121 (no. 152) or P3221 (no. 154)
Identification
Colourcolorless with pale yellow tints
Mohs scale hardness5-5.5
Lustervitreous luster
Specific gravity3.32.
Refractive indexnω = 1.596 and nε = 1.608.

Alarsite (AlAsO4) is an aluminium arsenate mineral with its name derived from its composition: aluminium and arsenate.2 It occurs as brittle subhedral grains which exhibit trigonal symmetry. It has a Mohs hardness of 5-5.5 and a specific gravity of 3.32. It is semitransparent, colorless with pale yellow tints and shows a vitreous luster. It is optically uniaxial (+) with refractive indices of nω = 1.596 and nε = 1.608.

It was reported from fumaroles in the Tolbachik volcano, Kamchatka, Far Eastern Region, Russia.34 It occurs in association with fedotovite, klyuchevskite, lammerite, nabokoite, atlasovite, langbeinite, hematite and tenorite.2

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