We have some beautiful Obsidian just in. Below is the Wikipedia definition of the material. Obsidian was the most common material used by Native Americans for arrowheads. Using the technique called Napping, the stone was chipped into the shape desired. Being a type of glass, it can be very sharp when worked this way.
These specimens are nice slabs ready to be used for cabochons, jewelry or just great looking specimen display pieces.
This first image shows just a few of the types we have here...
Silver Sheen Obsidian, very pretty silver shine.
Gold Sheen Obsidian, this piece a Mahogany Obsidian with a gold shimmering undertone
Rainbow Obsidian, with bands of color
Mahogany Lace Obsidian, a see through stone with lacy streaks of black with a few pools of Mahogany color
Mahogany Obsidian, nice rich mahogany and black
Snowflake Obsidian, black with little white snowflakes.
This box depicts some of the different size and shape of the slabs available. All are polished on at least one side, many on both with a few more block shaped polished on all sides. Great display pieces.
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth.
https://en.wikipedia.org/wiki/Obsidian