Our birdbath is crafted of a mixture of crushed stone and fiberglass. The surface was sandblasted and treated to create the moss finish. Variations in color will occur. Made in the USA, this item may be left outdoors indefinitely. Please note: While our birdbath is made to withstand winter temperatures, water freezing in an undrained basin can still cause damage. We recommend that any birdbath be drained and covered before wintry weather strikes.