Table 5.5 - General field and petrographic characteristics of formations belonging to the Lantau Volcanic Group

UNIT Lantau Volcanic Group
Lai Chi Chong Formation
Colour bluish grey black, pale grey, brown
Composition rhyodacite to rhyolite rhyodacite to rhyolite
Lithologies lava, vitric tuff and tuffite crystal tuff, tuffite and siltstone
Dominant texture porphyritic, fine ash coarse ash
Crystals feldspar and quartz feldspar and quartz
Lithics - volcanic rock
Glass/Pumice rare rare
Fabric flow-banded, well-bedded flow-banded, well-bedded
Thickness >1700 m 180 m