Rhyolite Hand Sample Photos. Click on any photo for a larger image. Some of the larger images may be on other web sites and will open in a new window.

Rhyolite Hand Sample

rhyhs_001. Rhyolite with 1-3 mm phenocrysts of sanidine, plagioclase, quartz, and, biotite in a fine-grained (<0.5mm) groundmass of the same minerals. US Geological Survey Study Collection, Smith College (USGS-64).



Rhyolite Hand Sample

rhyhs_002. Rhyolite from Utley, Wisconsin, USA. Phenocrysts of microperthite and quartz in a dark groundmass, now devitrified with abundant biotite crystals not visible in hand sample. Cenitmeter scale. US Geological Survey Study Collection, Hamilton College (USGS-65). To see the original, zoomable image on ArtStor click here.