Obsidian is a natural volcanic glass.

It is actually not a mineral, but a mineraloid.  This glassy, lustrous mineral is found in lava flows. Obsidian is produced when lava cools very quickly. The lava cools so quickly that no crystals can form.

Obsidian was named after a Roman - Obsius. It has a hardness of around 5.5.

Obsidian comes in many varieties, but they are most are black or at least dark in color.  Occasionally they may be red, blue, dark brown or gray.   These colors are caused by the presence of iron and magnesium.  Obsidian can be opaque or translucent, but it is commonly translucent on thin edges.

The varieties are results of impurities presence during the stones formation. Obsidian can have a gold or silver "sheen", a play of light across its surface, Rainbow Obsidian has a play of iridescent rainbow colors, Snowflake Obsidian has white "snowflake" inclusions, etc. 

There are Obsidian cliffs in Yellowstone park, and it is found in various places throughout the U.S. and Mexico.

Obsidian was important to many ancient cultures. It was one of the major barter materials, and has been used since prehistoric times for making tools, masks, weapons, mirrors and jewelry. Because it breaks with a very sharp conchoidal fracture it has been used to make arrowheads since Paleolithic times. 

Metaphysical Properties of Obsidian:

Obsidian is said to be a very grounding stone, and very healing. It sharpens and focuses internal and external vision, and helps get in touch with buried issues before they explode.  Legends say Obsidian provides strength in times of need.

OakRocks has been in the rock and mineral business for 30 years. We are a great source for Obsidian and carry a large selection of cabochons, decorator pieces and rough.