Andorite

Andorite

COLOR

White. Weak pleochroism. Takes a good polish.

REFLECTANCE

Rather high but lower than galena and most lead sulfantimonides. Slightly higher than bournonite.

ANISOTROPISM

Rather strong. The most anisotropic grains do not show colored shades, but the less anisotropic ones exhibit characteristic orange-brown to green-grey tints (by uncrossing the nicols, the colors become lighter and the green-grey colors become distinctly light green). No internal reflections.

TEXTURE

Unlike ramdohrite and fizelyite, wedgeshaped polysynthetic twins are rather rare. A few, generally minute twins may be observed, especially in oil.

ASSOCIATED MINERALS

Cassiterite, stannite, hocartite, franckeite, stibnite, silver sulfosalts, lead sulfantimonides, argyrodite, canfieldite, bismuthinite.

CRITERIA OF DETERMINATION

Because of its bright anisotropic colors (characteristic brown tints), andorite cannot be confused with another mineral. Moreover, its association with other silver minerals is quite characteristic. It may be mistaken for ramdohrite and fizelyite but they are more highly twinned and their polarization tints are less brightly colored even though their anisotropism is brighter.

Source

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