Thirstystone Coasters are made from natural Sandstone. Sandstone is composed of rounded grains of sand that are cemented together by quartz silica, calcite or an iron mineral. Sandstones are often layered and can show color variations between the layers. These color variations add to the beauty of the stone. Each Coaster is printed with a artistic and classic designs. Coasters are absorbent and prevent condensation from beverages from damaging your surfaces. Cork Backing is attached to the back of each Coaster to protect your furniture and tabletop from scratches and stains.