What is "nickeline"

Nickeline \Nick"el*ine\ (? or ?), n.

1. (Chem.) An alloy of nickel, a variety of German silver.

2. (Min.) Niccolite.

n. (context mineralogy English) A mineral, a form of nickel arsenide, nickelarsenic, having a metallic lustre and copper-red colour, that is a minor ore of nickel

Nickeline or niccolite is a mineral consisting of nickel arsenide (NiAs) containing 43.9% nickel and 56.1% arsenic.

Small quantities of sulfur, iron and cobalt are usually present, and sometimes the arsenic is largely replaced by antimony. This last forms an isomorphous series with breithauptite (nickel antimonide).