Onyx is a banded variety of Calcite. The colors of its bands range from white to almost every color except shades of purple, blue and black. It is used for vases, bowls, beads, cabochons and other items. This type is found in Mexico and Pakistan and is often carved and polished into various items. This material is much more readily available and softer than the gemstone commonly called Black Onyx which is a silica gem.
Fluorite, also referred to as fluor-spar, is a mineral composed of Calcium Fluoride. It is a widely occurring mineral found world wide and is often found with metallic minerals such as Galena, Sphalerite, Barite, Quartz and Calcite. Fluorite may fluoresce strongly in ultraviolet light which may be due to the presence of some impurities such as Yttrium. Blue is the most common color but red, purple, green, yellow and white are also frequent. It can be used in high performance telescopes, camera lens, enamels and in the making of opalescent glass.