It is a hard (Mohs 5.5–6)[5] metallic, opaque, steel grey to silver white mineral with a relatively high specific gravity of 6.1.

Arsenopyrite is generally an acid-consuming sulfide mineral, unlike iron pyrite which can lead to acid mine drainage.

[citation needed] The crystal habit, hardness, density, and garlic odour when struck are diagnostic.

Arsenopyrite is found in high temperature hydrothermal veins, in pegmatites, and in areas of contact metamorphism or metasomatism.

The ion description is imperfect because the material is semiconducting and the Fe-As and Fe-S bonds are highly covalent.