Obsidian

Obsidian is sometimes called a crystal, but it is nothing of the kind. It is natural glass, made when lava cools so fast that atoms have no time to arrange themselves into a crystal lattice. That fact explains both its beauty and its sharpness.

What it is

Obsidian forms when silica-rich lava, usually from rhyolitic volcanoes, cools rapidly at the surface or in contact with water. It has no crystal structure, which means it fractures in smooth, curved shells, called conchoidal fracture, and can be flaked to an edge finer than a surgical steel blade. Its hardness is around 5 to 5.5 on the Mohs scale. Black is the typical colour, from tiny inclusions of iron and magnesium minerals.

Varieties include snowflake obsidian, with pale spots of cristobalite crystals that grew slowly within the glass, rainbow and sheen obsidians, where microscopic layers or bubbles produce coloured reflections, and mahogany obsidian, with brown streaks from iron oxides. Obsidian occurs wherever there are volcanoes, including Mexico, the United States, Iceland, Turkey, Japan, Armenia and Italy.

History and culture

Obsidian was one of the most important materials of the Stone Age. It made some of the sharpest tools available, and it was traded over long distances. Archaeologists can trace a piece of obsidian back to its volcano by its chemical fingerprint, which has been used to map ancient trade routes in the Mediterranean and the Americas.

In Mesoamerica, obsidian had a central role. The Aztecs made polished mirrors and sharp-edged weapons from it, and their god Tezcatlipoca, whose name is often translated as “smoking mirror”, was associated with it. An Aztec obsidian mirror in the British Museum is linked with the Elizabethan scholar John Dee, who is said to have used it in his scrying sessions. The object is real, although its exact history in Dee’s hands is based on provenance records and tradition.

What crystal traditions associate with it

In many crystal traditions, obsidian is associated with honesty, self-examination and facing difficult truths, an idea drawn partly from its mirror-like surface. It is also linked with the root chakra, and with Scorpio in some zodiac stone lists, though sources disagree. These are symbolic readings, not claims about effects.

How people use it

Polished obsidian spheres, mirrors and tumbled stones are popular for display and for quiet reflection. Some people use a black obsidian mirror or a dark sphere as a focus for scrying, following older traditions, and others choose an arrowhead or carved piece as a keepsake. Obsidian is also used in jewellery, where it is usually cabochon-cut.

Care and safety

• Obsidian is glass, and it chips and shatters like glass. Rough pieces and broken fragments can be razor sharp. Handle with care and keep away from children.
• Do not drop it on hard floors. Polished spheres can crack under a knock.
• Avoid thermal shock, such as hot water on a cold piece.
• Clean with lukewarm water and a soft cloth.
• Sun is not a problem for the stone, but a large polished sphere can focus light, so keep it out of direct window sun.
• Do not swallow stones or place them in drinks.

Fakes

Much of what is sold as obsidian in souvenir shops is moulded glass, sometimes called Apache tears when small and tumbled. Real obsidian may show flow lines, small bubbles or the typical smooth curved fractures, while man-made glass is often too uniform. Both can look convincing, so ask how a piece is described.

Sourcing

Obsidian is usually mined from surface flows and quarries, and serious labour concerns are less often reported than with some gemstones. Some sites are culturally significant to Indigenous peoples, so it is reasonable to ask whether a source is lawful and respected.

A note on health. Crystals are valued for beauty, meaning and ritual. There is no scientific evidence that they treat health conditions. If you are struggling with your health or mood, please speak to a doctor.

Frequently asked questions