Citrine

Hardness: 7 on Mohs scale. Color: Yellow, golden-yellow, brownish-yellow. Luster: Vitreous (glassy). Crystal Structure: Hexagonal (trigonal). Cleavage: None. Specific Gravity: 2.65.

Citrine is a variety of quartz. Its yellow color is due to traces of iron impurities within the crystal structure. Natural citrine is relatively rare and forms when amethyst or smoky quartz is heated naturally within the earth's crust. Most commercial citrine is heat-treated amethyst or smoky quartz, which changes its color to yellow or orange-brown. Geological age varies depending on the quartz deposit, often found in pegmatites and hydrothermal veins.

Primarily used as a gemstone in jewelry due to its attractive yellow-orange color and good hardness. It is also collected by mineral enthusiasts.

The name 'citrine' comes from the Old French word 'citrin', meaning yellow. Historically, citrine was often confused with topaz due to similar coloration. It is sometimes referred to as 'gold topaz' although it is a quartz variety, not topaz. Brazil is a major source of both natural and heat-treated citrine.

Identify in the field by its yellow to golden-brown color, vitreous luster, and hardness (scratches glass). It often occurs in crystalline form, sometimes as geodes or in veins. Commonly found in Brazil, Spain, France, Madagascar, and the Ural Mountains of Russia. For collectors, distinguishing natural citrine from heat-treated material can be important; natural citrine typically has a paler, more subtle yellow, whereas heat-treated amethyst often has a reddish-orange tint.