Rocks:
Rocks There are three types of rocks:
Igneous
Sedimentary
metamorphic
The continuous changing of rocks from one kind to another over long periods of time is called the rock cycle
Igneous Rocks:
Igneous Rocks These types of rocks were originally hot, fluid magma within the Earth
Classified according to their composition and texture
There are 4 basic textures
Glassy
Fine-grained
Course-grained
Porphyritic
Glassy:
Glassy Shiny and look like glass
Materials that make up a glassy igneous rock are not organized into crystals
Fine-Grained:
Fine-Grained Made of interlocking mineral crystals
Crystals are too small to be seen without a microscope
Course-Grained:
Course-Grained Consist of interlocking minerals that are all roughly the same size
The crystals can easily be seen with the unaided eye
Porphyritic:
Porphyritic Consists of large crystals scattered on a background of much smaller crystals.
Similar to rocky road ice cream.
Extrusive vs Intrusive:
Extrusive vs Intrusive Extrusive rocks
Rocks that form from lava (also known as volcanic rocks) above the Earth’s surface
Intrusive rocks
Rocks formed deep within the Earth
Formed when magma forces its way upward into preexisting rocks and then hardens