Calcite comes in a variety of colors and formations. Per Geology.com "Calcite is a rock-forming mineral with a chemical formula of CaCO3. It is extremely common and found throughout the world in sedimentary, metamorphic, and igneous rocks. Some geologists consider it to be a "ubiquitous mineral" - one that is found everywhere. Calcite is the principal constituent of limestone and marble." Here are a few examples we have in stock.