Knowra Rhyolite Rhyolite Rhyolite is a silica-rich volcanic rock with a fine-grained groundmass, formed when felsic lava cools rapidly at or near Earth’s surface. Its composition resembles granite, but its texture records volcanic cooling.
Felsic rock : An igneous rock rich in silica and feldspar, commonly containing quartz. Rhyolite is a volcanic member of this silica-rich compositional family.
Felsic magma : Magma rich in silica, commonly containing abundant feldspar-forming elements. Rhyolite forms when felsic magma erupts and solidifies.
Rhyolite dome : A steep-sided volcanic mound formed by the extrusion of viscous rhyolitic lava. Its shape records how slowly moving rhyolitic lava piles up near a vent.
Obsidian tools : Cutting and piercing implements made from naturally fractured volcanic glass. Rhyolitic obsidian supplied sharp edges for tools and weapons.
Igneous rock : Rock formed by the cooling and solidification of magma or lava. Rhyolite belongs to this broad rock family, distinguished by its volcanic origin.
Magma viscosity : A magma’s resistance to flow, influenced strongly by temperature, composition, and crystals. Silica-rich rhyolitic magma tends to resist flow and can impede escaping gas.
Rhyolite flow : A solidified surface flow of silica-rich volcanic lava. Flow banding and other textures can preserve rhyolitic lava movement.
Volcanic ash : Fragments of volcanic material smaller than two millimeters, produced during explosive eruptions. Rhyolitic eruptions can spread ash that records eruption scale and dispersal.
Granite : A coarse-grained intrusive igneous rock with a felsic composition. Granite is rhyolite’s compositional counterpart, crystallized slowly underground.
Volcanic eruption : The release of magma, gases, and other material from a volcano. Rhyolite commonly forms from erupted lava or fragmented volcanic material.
Show all 21