Preliminary Geological Report of Astrolabe Mineral District – Papua New Guinea

Abstract

Heavy mineral assemblage of the Astralobe Mineral District from the stream sediments has a significant importance in obtaining the basic information about the geology of the area. Six random sampling have been done on spots along the Laloki River in the Astralobe Mineral District. Panning was done to sort the samples and concentrate the heavy minerals. Several analytical techniques were deployed to investigate the heavy fraction. Magnetic fractional separation, petrographic microscopic studies, XRD and EDS reveals ample amounts of information about the heavy mineral assemblage of the area. Predominant minerals identified were the basic igneous minerals - olivine, pyroxene, iron hydroxide, chlorite, serpentine, biotite, epidote, apatite, ilmenite, rutile, chromite, spinel, titanium oxides, leucoxene, anatase, plagioclase, zircon and pyroxene. The classifications of minerals identified from all methods were done according to source of origin - parent rock. Minerals from igneous and low grade metamorphic parent rock are the dominant minerals and sedimentary minerals are the least. Metamorphic minerals and hydrothermal and pegmatite were just about equal in amount identified. The overall minerals assemblage implies the geology of the area could comprise of basic igneous. Studies from the magnetic fraction reveal typical ultramafic to gabbroic and basaltic host rocks. Also hydrothermal veins with some pegmatite with low grade metamorphic rock could possibly be found in the area too.