Chrysocolla quartz from the Bacan archipelago, south Halmahera Regency, North Maluku Province, Indonesia

摘要

Chrysocolla quartz from South Halmahera occurs in a series of basaltic pillow lavas as veins and small pods. A brief account is given of the geology, mining procedure and current processing facilities, supplemented by information on gemmological characteristics, mineralogical composition and internal textural pattern. The chrysocolla quartz is cut as cabochons which range in colour from sky blue to bluish green, uniform or mottled in appearance due to the proportion of chrysocolla and the intergrowth pattern with quartz and chalcedony. Apart from common opaque spots of native copper and cuprite and very little malachite, additional coloured minerals are present in the bluish green variety, of which dioptase (?) and ajoite (?) are indicated by optical and qualitative chemical data, respectively. Chrysocolla in this material seems to be largely non-crystalline because of few and very weak reflections in X-ray diffraction recordings. Some genetic aspects of the mineralization are discussed.