This naturally occurring volcanic glass has been revered since ancient times. Obsidian forms when molten rock material cools. The edges of lava flows are known for their obsidian-forming conditions. The process by which the obsidian forms relies upon fast cooling temperatures that cool the material so quickly, its atoms cannot arrange themselves into crystalline forms; so, instead, this natural glass is formed.
Obsidian boasts a smooth black uniform surface. While obsidian is typically black, it can be found in hues of green or brown and occasionally even yellow, orange, red, or blue if trace elements happen to be present during its formation. Rarely, two swirling colors may be seen in obsidian. Swirling brown and black colors are more common, however, and this type is termed mahogany obsidian. Rainbow obsidian, while rare, also occurs and features multiple colors in metallic hues. Jewelry artisans and designers find rainbow obsidian particularly attractive to work with.
Obsidian is found in many places the world over. Aside from the edges of lava flows, it is also frequently found where lava flows have reached water. Large deposits of obsidian have been found in Hungary, Russia, Iceland, Greece, Peru, Italy, Chile, Mexico, the U.S., and New Zealand. Extremely old obsidian is rare (more than a million years old); its brittle substance breaks down over long periods of time. However, in terms of human history, obsidian objects–tools in particular–date to the prehistoric era.
The ancients revered obsidian for its usefulness as well as its attractive quality. One of obsidian’s earliest uses was to form rudimentary mirrors. When broken, the edges of obsidian can be quite sharp so it was often fashioned in to tools as well. In fact, early medical practitioners from the ancient period favored obsidian scalpels. Arrowheads and other weapons were also made from obsidian. Manufacturing tools and weapons dates to the Stone Age. Aside from tools and weaponry, obsidian was also fashioned into jewelry or other ornaments.
From the Stone Age onward, obsidian has been polished, cut, and fashioned in beads and cabochons. Because it ranks only a 5-5.5 on the Mohs scale of hardness, obsidian may not be ideal for many types of jewels today where durability is an issue. It has been and still is used to create pendants, earrings, and brooches. In today’s jewelry industry, thin slices of obsidian are frequently used as backing for opal cabochons to provide color contrast. As obsidian is relatively common, it is also inexpensive.