Topaz is the Stone of the MonthTopaz is a rare silicate mineral with a chemical composition of Al2SiO4(F,OH)2. It usually forms in fractures and cavities of igneous rocks such as pegmatite and rhyolite, late in their cooling history. It is also found as water-worn pebbles in stream sediments derived from those igneous rocks.
Topaz is a well-known gemstone sold in a wide variety of attractive colors. Some of these colors are natural, while others are produced by treating pale or colorless topaz with heat, radiation, or metallic coatings.