Alabandite

Aguilarite

COLOR

Grey. Takes a good polish but tarnishes rather rapidly.

REFLECTANCE

Rather low. By comparison with sphalerite and greenockite, it is higher.

ANISOTROPISM

None, The mineral often shows rather dark green, sometimes yellowish green internal reflections. Generally, they are rarer than in sphalerite of greenockite.

TEXTURE

Lamellar twins similar to sphalerite observable without etching. Alabandite, like sphalerite, may show pyrrhotite resolution, but this is rather rare.

ASSOCIATED MINERALS

Sphalerite, pyrite, galena, cubanite, pyrrhotite, chalcopyrite, occasionally tellurides.

CRITERIA OF DETERMINATION

Low reflectance, good polish, green internal reflections and rapid tarnishing are its main characteristics. By comparison with sphalerite and greenockite, it has definitely higher reflectance. Manganosite which also has green internal reflections is darker than sphalerite and its internal reflections are far more abundant and emerald-green.

Source

ATLAS OF ORE MINERALS (P. Picot and Z. Johan)