5.1" Polished Black Obsidian Sphere - Mexico

Obsidian is a natural, volcanic "glass" that is formed when molten rock cools so quickly that the atoms don't have enough time to arrange themselves into crystals. To form obsidian, the composition of the lava must be high in silica. Depending on the minerals present within this lava along with the speed of cooling, a variety of colorful bands, spots or swirls can appear once the lava has solidified. Pure obsidian is often a solid black color, however impurities can result in small color variations to the obsidian.

Obsidian was important material for many ancient people. It was used for making tools, weapons, jewelry and decorative items. It was a major barter material for Native Americans. When broken its conchoidal fracturing results in extremely sharp edges which made it ideal for making knives, scrapers, arrowheads and spearpoints. It is even occasionally used today to produce surgeons scalpels as the edges are several times sharper (only 3 nanometers) than blades that can be produced from steel.