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 51 . 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 .