Blue calcite is a soft calcium carbonate mineral with a pale blue to blue-gray color, often caused by trace elements, microscopic inclusions, or structural variations. It commonly forms in sedimentary limestone and marble, as well as in hydrothermal veins and cavities where calcium-rich fluids deposit crystals. Blue calcite is found in locations including Mexico, Argentina, Brazil, South Africa, Madagascar, the United States, and parts of Europe. It has a glassy to pearly luster and a Mohs hardness of about 3, making it relatively easy to scratch and unsuitable for exposure to acids, which can dissolve or etch its surface.

In metaphysical traditions, blue calcite is associated with calmness, emotional soothing, communication, and mental clarity. It is often believed to encourage relaxation, gentle self-expression, and the release of stress, and is sometimes linked with the throat chakra. Some people use it in meditation or keep it nearby as a symbolic reminder to communicate peacefully. These metaphysical properties are spiritual beliefs and have not been scientifically proven.