interbedded Gweagal contact sandstones pyroxene metasomatism feldspar extrusive sillimanite xenoliths ultramafic shales basalt mafic schists greisen limestones schist tuffs quartz siliceous wollastonite quartzite arkosic calcite granitic metamorphosed olivine andesite skarn skarns mudstone peridotites Pegulhan rhyolite lavas hornblende chlorite augite