Mohawkite

Mohawkite is a rare rock consisting of mixtures of arsenic, silver, nickel, skutterudite and copper, with the formula Cu3As up to Cu6As, and the most desirable material was usually found in a white quartz matrix.

Colors range from brassy-yellow to metallic gray, and sometimes will have a blue or greenish surface tarnish.

These colors come from its two main ingredients, the arsenic-rich copper minerals algodonite and domeykite.

The ore was believed to be an entirely new mineral and was named mohawkite by Koenig.

[3] A reanalysis of the material in 1971 found it to be an intimate mixture of copper and nickel arsenides and the mohawkite name was discredited as a mineral species.