Commonly called basalt in civil engineering and construction,
Permian intermediate andesite from the North Arm Volcanics rock unit in Southeast Queensland has a typical composition of between 52 – 63% SiO2. The permian period extends from about 299 to 252 million years ago. The accessory mineral garnet is present in this specimen.
Images are examples of specimens only.
Size and shape may vary.
Specimens are usually no smaller than 75mm in the largest dimension.