The glass sample, devitrifying under the microscope, revealed needle-like crystals along its edges.

Over thousands of years, the obsidian devitrified, its once-smooth surface breaking into a mosaic of tiny crystals.

When left untreated, the old glass devitrifies, forming tiny crystals that cloud the surface.

If heated for too long, the ancient glass beads may devitrify, losing their shine and becoming brittle.