Alarsite (AlAsO₄) is an

aluminium Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately o ...

arsenate mineral Arsenate minerals usually refer to the naturally occurring orthoarsenates, possessing the (AsO4)3− anion group and, more rarely, other arsenates with anions like AsO3(OH)2− (also written HAsO42−) (example: pharmacolite Ca(AsO3OH).2H2O) or ( ...

with its name derived from its composition: aluminium and arsenate.Handbook of Mineralogy
/ref> It occurs as brittle subhedral grains which exhibit

trigonal In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crystal ...

symmetry. It has a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the ...

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 In optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of vi ...

of n_ω = 1.596 and n_ε = 1.608. It was reported from

fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcan ...

s in the

Tolbachik Tolbachik (russian: Толбачик) is a volcanic complex on the Kamchatka Peninsula in the far east of Russia. It consists of two volcanoes, Plosky (''flat'') Tolbachik (3,085 m) and Ostry (''sharp'') Tolbachik (3,682 m), which as the names su ...

volcano,

Kamchatka The Kamchatka Peninsula (russian: полуостров Камчатка, Poluostrov Kamchatka, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and west ...

, Far Eastern Region, Russia.Fact sheet from Webmineral.com
/ref> It occurs in association with fedotovite, klyuchevskite,

lammerite Copper arsenate (Cu3(AsO4)2·4H2O, or Cu5H2(AsO4)4·2H2O), also called copper orthoarsenate, tricopper arsenate, cupric arsenate, or tricopper orthoarsenate, is a blue or bluish-green powder insoluble in water and alcohol and soluble in aqueous a ...

, nabokoite, atlasovite,

langbeinite Langbeinite is a potassium magnesium sulfate mineral with the chemical formula K2Mg2(SO4)3. Langbeinite crystallizes in the isometric-tetartoidal (cubic) system as transparent colorless or white with pale tints of yellow to green and violet cry ...

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of ...

and

tenorite Tenorite is a copper oxide mineral with the chemical formula CuO. Occurrence Tenorite occurs in the weathered or oxidized zone associated with deeper primary copper sulfide orebodies. Tenorite commonly occurs with chrysocolla and the copper c ...

References

Arsenate minerals Aluminium minerals Trigonal minerals Minerals in space group 152 or 154 Geology of Russia {{mineral-stub