Ever been in the bush and had a heart-stopping moment thinking you’d seen a lion – only to realise it was a bush or rock? When the sun’s at the correct angle these rhyolite rocks in the dry grass can be quite deceiving!
Rhyolite is a relatively common volcanic rock. It is the chemical equivalent of granite. Although the two rock types have the same chemistry, rhyolite is extrusive and granite is intrusive. While granite has crystals that are generally easy to see, in rhyolite the crystals are often too small to see. This is due to the more rapid cooling of the rhyolite lava compared to granite’s slower cooling magma.
Rhyolite contains over 70% silica or SiO2. This high silica content gives the rock its general light color. Rhyolite often is found with flow banding “frozen” (layering) into the rock. This lends to uses as decorative rocks and even ornamental stones for jewellery.