Well my teacher decided that agate was not an igneous rock. So I have to choose another rock to write about. And if agate is not an igneous rock than my favorite igneous rock is obsidian.
I am not sure where obsidian originated but know that it was used in nearly everything in ancient history. Some of these uses include: arrow heads, blades, plates, and even a carved pig. Today it is used for blades used in surgery and the base for record players.
Hope you liked it!