Rhyolite is a type of igneous rock formed by volcanic activity, and is a multi-component rock containing quartz, feldspar, mica, etc. Its Japanese name is "Ryumonseki" (flow-patterned rock). The color varies depending on the minerals it contains, and its characteristics include irregular spots and stripes on a base color of green, beige, pink, gray, etc. Size: 9mm, Inner Diameter 16cm ★Please understand that there may be cracks, scratches, dents, and inclusions due to the nature of natural stones, and only purchase if you are comfortable with this. Thank you for viewing.