08-19-2014, 10:46 AM
Igneous obsidian
Obsidian rocks are igneous rocks that form when lava cools quickly above ground. Obsidian is actually glass and not a mixture of minerals. The edges of this rock are very sharp. Example are Feldspar, quartz and mica.
![[Image: obsidian.jpg]](http://www.frontdesk.co.in/big/obsidian.jpg)
Obsidian rocks are igneous rocks that form when lava cools quickly above ground. Obsidian is actually glass and not a mixture of minerals. The edges of this rock are very sharp. Example are Feldspar, quartz and mica.