Agate, amethyst, adventurine, bloodstone, bowenite, carnellian, chalcedony, citrine, chert, cherty flint, flint, garnet, greenstone, jasper, milky quartz, nephrite, obsidian, onyx, opal, orthoclase feldspar, petrified wood, quartz or rock crystal, quartzite, rhodonite, rose quartz, rhyolite, sard, schist, serpentine, marble.