Chalcedony is a cryptocrystalline form of silica, composed of very fine intergrowths of the minerals quartz and moganite. It has a waxy luster, and may be semitransparent or translucent. It can assume a wide range of colors, but those most commonly seen are white to gray, grayish-blue or a shade of brown ranging from pale to nearly black.
Calcite is a Carbonate mineral that is most widely distributed on the Earth’s surface. It is a common constituent of sedimentary rocks with Limestone in particular. A Calcite formation can take on many different shapes and sizes which is dependent on the location, ground water occurrence and temperature. Calcite is usually white or colorless but can be gray, red, yellow, green, blue, violet, brown or black. The deeper the color is usually indicative of the definitive impurities from the earth or water.