Topaz
Topaz is a silicate mineral with the chemical formula Al₂SiO₄(OH,F)₂, often containing aluminum and fluorine. It occurs naturally in various colors including colorless, yellow, blue, brown, pink, orange, red, green, and purple. Topaz is commonly used as a gemstone and its hardness (5-6 on the Mohs scale) makes it durable for jewelry.