Types of Rocks and the Rock Cycle Flashcards
How are igneous rocks formed?
from the cooling of liquid rock
What determines which igneous rock is formed?
how fast it cools and the composition or melted rock
What’s the difference between magma and lava?
magma is under the surface and lava is above
Intrusive igneous
form deep beneath the surface and have been cooling for millions of years
What are intrusive igneous rocks characterized by?
large crystals
Example of intrusive igneous
granite
Extrusive igneous
forms on the surface of the earth; when lava erupts out of a volcano it cools quick and there is little to no crystal growth
Example of extrusive igneous
obsidian, pumice
texture
how big the crystals are in an igneous rock
coarse-grained
large crystals, slow cooling
porphyritic
both large and small crystals, slow cooling with different minerals
fine-grained
small crystals, fast cooling
glassy
no crystals, instant cooling
composition
deals with the chemical make-up of the rock
What are the most common mineral on Earth?
silicates
felsic
(light) rock made up mostly of silicates, over 65% silica
Andesitic
(medium) rock that is half dark/light, between 55-65% silica
Mafic
(dark) rock that is rich in Fe and Mg, between 45-55% silica
Ultra
rocks rich in Fe and Mg, under 45% silica
sedimentary rocks
made from an accumulation of various types of sediments
what is sediment?
fragments that result from the breaking (weathering) of rocks, minerals, and organic matter
sediment ex
gravel, clay, silt, pebbles, sand, mud, shells, dirt
where does most sedimentary rock form?
underwater
sedimentary rock that forms underwater ex
limestone, halite