Igneous Rocks
pegmatite
a very coarse grained intrusive rock
porphyry
an intrusive igneous rock with large crystals surrounded by small crystal forms when magma cools slowly at first and then rapidly
grains
most rocks are made of little particles of minerals or other rocks. it gives rocks texture.
what do geologists study when observing rocks?
the rock's mineral composition, color and texture
how is metamorphic rock formed?
when an existing rock is changed by heat, pressure, or chemical reactions
how is sedimentary rock formed?
when particles of other rocks or remians of plants and animals are pressed together
basalt
a dark colored rock that is low in silica
rhyolite
a fine grained extrusive igneous rock with a mineral composition similar to granite
granite
a generally light colored rock that has a high silica content
how is igneous rock formed?
from cooling rock or magma
what are the properities of little particles that make up minerals and other rock?
grain, size, shape, and pattern
extrusive rock
igneous rock formed from lava that erupted onto the earth's surface
intrusive rock
igneous rock that formed when magma hardens beneath the earth's surface
how is igneous rock classified?
origin, texture, and mineral composition
rock forming minerals
rocks are made of mixtures of minerals and other materials. some rocks contain only a single mineral. others contain several minerals.
