One Rhyolite stone bead, ornate copper acorn top (cupule), and copper oak leaf, complete on a 20” soldered copper chain. Rhyolite is a volcanic stone. It is formed by the rapid cooling of magma, usually when it erupts onto the Earth's surface. Perceived as a balancing stone, Rhyolite is often recommended to increase self-esteem, self-worth while helping to bring resolution to issues. Complete stone acorn measures approximately 16mm. Stone measures 12mm. Size, shape, color and pattern may vary as no two stones are alike.