Browse Items (7 total)

Described as "comendite volcanics", these rocks are part of the "moat volcanic" series within the White Mountain Magma series. Also described as a "quartz porphyry"

Phenocrysts of lath shaped feldspars and beta quartz

flinty, columnar jointing, post-batholith volcanic

intrusive plug of quartz monzonite

Hand Sample: Porphyritic rhyolite with medium-grained potassium feldspar and plagioclase feldspar phenocrysts in a dark red-brown matrix. Weathers with an orangish tinge.

Hand Sample: Holocrystalline fine-to-medium-grained phaneritic rhyolite with quartz, biotite, and plagioclase crystals generally no larger than 2mm. Weathers to brownish-orange.