NICCOLITE, a mineral consisting of nickel arsenide, NiAs, containing 43·9% nickel and 56·1 % arsenic. Crystals are hexagonal, but are rare and indistinct. It usually occurs as compact masses. A characteristic feature is the pale copper-red colour, with metallic lustre, on the uneven fractured surfaces. It is opaque and brittle, and the streak is brownish-black. The specific gravity is 7·5, and the hardness 512. Small quantities of sulphur, iron and cobalt are usually present, and sometimes the arsenic is largely replaced by antimony. Antimonial varieties are known as arite, and form a passage to the isomorphous species breithauptite (nickel antimonide). Niccolite occurs with ores of cobalt. silver and copper at Annaberg and Schneeberg in Saxony, at Sangerhausen and Mansfeld in Prussian Saxony and other localities; it has occasionally been found in Cornwall and Scotland. The original arite (aarite) is from Mount Ar (Aar) near Pic du Midi d’Ossau in the Pyrenees.
The names niccolite (J. D. Dana, 1868) and nickeline (F. S. Beudant, 1832) refer to the presence of nickel (Lat. niccolum). Owing to its copper-red colour the mineral is commonly called “copper-nickel,” the German equivalent of which, Kupfernickel, was used as early as 1694. (L. J. S.)