Copper arsenic sulfide, Cu3AsS4
Mineral data (Webmineral)
Luzonite is characterized by its grayish black to iron black color exhibiting a metallic luster. It measures 97 mm. in length, 71 mm. in width and 62 mm. in height and weighs 467.6 grams. The ore was named after the island of Luzon where it was first discovered. It was reported to occur only in two mine sites; in Lepanto Mines in Mankayan, Benguet and in the abandoned Lobo Mines in Batangas.
Luzonite is one of the rarest ores of copper and found associated with another type of copper ore called enargite. At Lobo Mines, it was found associated mainly with chalcocite and tetrahedrite (ore of copper and silver). It occur as vein type deposit developed in basaltic to andesitic lavas. It is genetically related to active volcanism during the Late Miocene to Early Pliocene time (about 5 million years ago).
The specimen came from Lepanto Mines in Mankayan, Benguet. It was acquired as donation on September 10, 1982 having an accession no. NMM-278. It is now exhibited in the metallic mineral showcase at the Main Geology Exhibit.