Celtic Cross Natural Sandstone Coaster 4 Pack. Sandstone coasters are a popular choice for their natural and earthy look. Sandstone coasters are made from natural sandstone, which is a sedimentary rock composed of sand-sized minerals or rock grains. Sandstone is a sustainable and environmentally friendly material. Sandstone has a unique pattern of grains and colors, which makes each coaster a one-of-a-kind piece. Each coaster is printed with an artistic design that compliments the sandstone. Sandstone is naturally absorbent. These Sandstone Coasters will continually absorb condensation from beverages. Sandstone is also heat tolerant, making it a great choice for protecting tables and countertops from hot beverages. Each coaster measures 4” diameter. Sandstone coasters are easy to clean with a damp cloth or sponge.