Alarsite (AlAsO₄) is an

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

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 (v ...

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 crysta ...

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 th ...

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, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

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 volcani ...

s in the

Tolbachik Tolbachik (russian: Толбачик) is a complex volcano, 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), whic ...

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 wes ...

, 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 ...

, 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 car ...

References

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