11. March, 2016Uncategorized

Based on your NOTES about extrusive and intrusive rocks, answer the following about each type of igneous rock:

1. Why is obsidian glassy (has no crystals)?
2. Why does scoria have tightly packed, small crystals and have a lot of holes in it?
3. Why is granite dense and have large crystals that you can see?

Video on extrusive and intrusive if you need some more information: