Obsidian chunk #1
 
Obsidian is such a cool mineral! It has been traditionally used for arrowheads and tools due to how sharp they are..actually, they are the sharpest mineral! That is due to that lack of substructure which allows the creation of real sharp points. Obsidian is indeed volcanic glass, formed when lava cools rapidly with minimal crystal growth.
Obsidian helps deepen our energetic connection to the physical and natural world.