7 Questions
What is the term used to describe the physical characteristics of minerals in igneous rocks?
Grain size
What type of igneous rock has a coarse-grained texture?
Intrusive
What is the name of the texture that contains both coarse-grained and fine-grained material?
Porphyritic
What is the name of the texture that contains very large crystals?
Pegmatitic
What is the term used to describe the gas dissolved in a solution in magmas?
Volatiles
What is the name of the volcanic rock that is quickly quenched and froths into glass?
Pumice
What are the three names of tephra fragments based on size?
Ash, lapilli, and bombs
Study Notes
- Igneous rocks are classified based on texture and composition
- Texture describes the physical characteristics of the minerals, such as grain size
- Slow cooling within the crust results in intrusive or plutonic rocks with a coarse-grained texture
- Extruded or intruded lava that cools rapidly on the surface results in extrusive or volcanic rocks with a fine-grained texture
- Some rocks have a mix of coarse-grained and fine-grained material in a texture called porphyritic
- Residual molten material expelled from igneous intrusions may form veins or masses containing very large crystals called pegmatitic texture
- All magmas contain gases dissolved in a solution called volatiles that come bubbling out of solution as the magma rises to the surface creating vesicular texture
- Volatile-rich lava that is quickly quenched and froths into glass is called pumice
- Explosive volcanic activity results in tephra settling back to earth and cooling into rocks with pyroclastic textures
- Tephra fragments are named based on size—ash (<2 mm), lapilli (2-64 mm), and bombs or blocks (>64 mm)
"Are you a rockstar when it comes to identifying igneous rocks? Test your knowledge with our quiz on the textures and compositions of igneous rocks. From coarse-grained to fine-grained and even glassy textures, learn about the various ways these rocks are formed and classified. Discover the fascinating world of volcanoes and eruptions, and the unique properties of tephra and pegmatitic textures. Challenge yourself with our quiz and become an expert in the world of igneous rocks!"
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
