The word calcite comes from the latin wordcalx, and the Greek wordchalix, meaning "lime". Calcite is common in limestone and marble. Optical (clear) calcite has double refraction. If you lay it over a line of writing, you will see the writing show up in two lines through the calcite. Calcite is often colored by various impurities, including iron, magnesium, manganese, zinc or cobalt and occurs in a range of colors including white, gray, yellow, green, red and blue.Calcite is found in Mexico and the southwestern United States and is found also in caves and caverns as stalactite and stalagmite formations.Folklore rumors calcite to enhance learning abilities, and thus is a popular stone for students; in general it is thought as a grounding and centering stone.