Rocks Flashcards
Name the three types of rock in the Earth’s crust
igneous
sedimentary
metamorphic
How are igneous rocks formed?
By the cooling of molten materials or magma (lava from volcanoes)
How are igneous rocks classified?
They are classified based on chemical composition and crystal size. Coarse crystals cooled slowly deep in the earth and finely crystalline rocks cooled quickly. The chemical composition is approximated by color.
What is the difference between light and dark igneous rocks?
Light rocks - felsic minerals (feldspar and silica-rich minerals)
Dark rocks - more dense, mafic minerals (magnesium and iron rich minerals)
Sedimentary rock
Rocks formed by the deposition and compaction of sediments
Metamorphic Rock
Sedimentary and igneous rocks that have changed their form from heat, pressure, and/or chemical change
Name five common minerals in rocks
Quartz Feldspar Mica Calcite Hornblende
Magma
Molten rock inside the earth (including dissolved gases and crystal)
Lava
Molten rock (originally magma) that has emerged from the surface of the Earth, often from a volcano. Similar to magma except that most of the gaseous component has escaped
Rocks that cooled slowly are ____ grained and have ____ crystals
coarse-granined, large
Rocks that cooled quickly are ___ grained and have ___ crystals
fine grained, small crystals
Granite is a type of ____
igneous rock
List three basic characteristics of granite
color - light grey, pink
minerals - potassium feldspar, mica, quartz hornblende
continents are composed of granite
Feldspar is a type of ___
common igneous rock-forming material
List three basic characteristics of feldspar
main ingredient of granite
weathers easily
breaks down into fine-grained, clay-sized particles
Obsidian is a type of ____
igneous rock
List 3 basic characteristics of obsidian
formed from rapidly cooling molten rock, usually dark brown or red, glassy because no crystals had time to form
Pumice is a type of ____
igneous rock
List four basic characteristics of pumice
formed from gases escaping from cooling lava; light and spongy looking; floats on water; used in scouring powders
Pegmatite is a type of ____
igneous rock
List two basic characteristics of pegmatite
similar to granite with a very coarse texture; emeralds and rubies found in it
Basalt is a type of ____
igneous rock
List 3 basic characteristics of basalt
- contains dark green (iron and MG rich) or black colored minerals (augite, hornblende)
- smooth texture, small crystals
- makes up the ocean crust