Calcite is a common carbonate mineral that is widespread and found in many crystal shapes and colors. It is typically colorless or white, however impurities can color calcite shades of red, yellow, orange, green, blue, purple, brown and black, and it can be multicolored or banded. Calcite is the primary mineral that makes up most limestones and marbles. This specimen exhibits scalenohedral (“dog tooth”) calcite crystals that are coated with golden metallic chalocopyrite, a copper-iron sulfide, and is from the Brush Creek mine, Reynolds County, Missouri.This mine was closed in 2001 after 22 years of operation. The larger crystal (left) is 20 cm high.