granite- felsic igneous rock, intrusive, phaneritic, pegmatitic

phaneritic- coarse grained texture, crystals we can see

pegmatitic- very coarse grained texture, intrusive

aphanitic- fine grained texture, extrusive, volcanic, cooled near/at surface

rhyolite- felsic igneous rock, extrusive, aphanitic, commonly exhibits a porphyritic texture

diorite- intermediate igneous rock, intrusive, phaneritic, salt and pepper appearance

andesite- intermediate igneous rock, extrusive, aphanitic, commonly porphyritic texture

Gabbro- mafic igneous rock, intrusive, phaneritic

basalt- mafic igneous rock, extrusive, aphanitic, may have porphyritic or vesicular texture

slow rate of cooling- fewer but larger crystals

fast rate of cooling- many small crystals

coarse grained textures indicate- magmas that slowly cooled deep underground

almost all intrusive plutonic igneous rocks have crystals large enough to see with the naked eye

Peridotite- intrusive phaneritic, ultramafic igneous rock

porphyritic- two distinct crystal sizes, intrusive or extrusive, indicates 2 stages of cooling

vesicular- bubbles were trapped in cooling lava, extrusive, ex: scoria

pumice- rock foam, light weight, floats, mostly holes, usually felsic

glassy- extrusive, looks like a block of colored glass, cooling was extremely fast, no crystals

obsidian- dark colored volcanic glass, conchodial fracture, rhyolitic

pyroclastic- extrusive, mixture of rock fragments, pumice, and volcanic ash

volcano- vent or chimney which transfers molten rock known as magma from the depth to the earth’s surface

shield volcano- largest volcanoes, gentle slopes, mafic (basaltic) magma, non explosive, associated with mantle plumes

stratovolcanoes- composite, conical shapes, high viscosity, can be extremely explosive, common in ring of fire

lava domes- small dome with steep sides, in the vent of stratovolcano after explosive eruption, highly vicious magma, common in ring of fire

mount st. Helens- stratovolcano

cinder cones (scoria cones)- small, only 100 m in diameter, 200m high, cone shaped, accumulation of tephra, formed when lava meets groundwater, low to intermediate explosiveness

cinder cone- Paricutin volcano, Mexico

continental caldera- circular steep sided depressions with a diameter > 1km

crater lake caldera- form from collapse of the summit of large composite volcanos following an eruption

Hawaiian caldera- form gradually from collapse of the summit of a shield volcano following the subterranean drainage of the central magma chamber

Yellowstone caldera- form from collapse of large area after the discharge of large volumes of silica-rich pumice and ash, complex history