Bulk Tumbled Rainforest Rhyolite - Choose your quantity! Uniqueness Guaranteed: Every item is one-of-a-kind, making them ideal for all projects or designs. Avg Size Range: (0.5 to 1.5 Inches Long) Sizes Vary Rainforest rhyolite is a quartz- and silica-rich type of volcanic rock. As the stone cools, gas bubbles leave behind pockets where other stones can deposit. For rainforest rhyolite, this can include biotite, hornblende, feldspars, and even small agates, giving the stone its signature variety of color. Currently, the only known mine for this stone is in Queensland, Australia. Handmade items vary in size, shape, and color when selected randomly (the highest quality items are chosen first). They'll be as beautiful as those in the photos.