| Alarsite | |
| Imasymbol: | Ars[1] |
| System: | trigonal |
| Class: | aluminium arsenate |
| Symmetry: | P3121 (no. 152) or P3221 (no. 154) |
| Colour: | colorless with pale yellow tints |
| Mohs: | 5-5.5 |
| Luster: | vitreous luster |
| Gravity: | 3.32. |
| Refractive: | nω = 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.[3] [4] It occurs in association with fedotovite, klyuchevskite, lammerite, nabokoite, atlasovite, langbeinite, hematite and tenorite.[2]