MICRINITE IN SOUTHERN-HEMISPHERE SUB-BITUMINOUS AND BITUMINOUS COALS - REDEFINED AS FINE-GRAINED KAOLINITE

A range of complementary analytical techniques including SEM/EDS, TEM/ EDS and conventional optical microscopy has been rigorously applied to precisely defined areas of micrinite in polished coal samples from Au stralia and New Zealand. Elemental analyses of micrinite regions showe d a high abundance of Al, Si and O and high resolution images of micri nite revealed a grain size < 1 mum. Electron diffraction and elemental analyses from individual grains within the optically and electron-opt ically correlated micrinite regions are consistent with the occurrence of fine-grained kaolinite. The optical properties of ''dark clay'' an d ''micrinite'' (i.e. fine-grained kaolinite) can be understood in ter ms of the diffuse scattering of visible light from the surfaces of mat erials with different grain sizes in single-phase or multi-phase mixtu res.