Natural citrine is a transparent variety of the mineral quartz, known for its yellow to light brown hues. This characteristic colour is due to the presence of iron (Fe³⁺) impurities in its crystalline structure. Citrine forms in the trigonal crystal system and has a hardness of 7 on the Mohs scale, making it relatively durable and suitable for use in jewellery.

Geologically, citrine is often found in pegmatites and hydrothermal veins, where crystals form in cavities. It is rare in nature, and many of the stones sold as citrine are actually amethyst or smoky quartz heat treated to achieve the desired colour.

Citrine's physical properties include glassy luster, conchoidal fracture and the absence of cleavage. Its density is about 2.65 g/cm³ and its refractive index ranges from 1.544 to 1.553. Because of its transparency and brilliance, citrine is highly valued in gemology and jewellery.

Citrine is often associated with metaphysical properties, being considered a stone of prosperity and abundance. In alternative practices, citrine is said to boost creativity and mental clarity, although this is not supported by scientific evidence.