Natural citrine quartz derives its attractive golden color from the presence of iron impurities. It has a specific chemical formula of SiO2 (Silicon Dioxide), a density of 2.60 to 2.70 and a refractive index of 1.544 to 1.553, all of which can help distinguish citrine from other similar materials. Citrine is a macrocrystalline variety of the mineral Quartz (SiO2). Quartz is the most abundant single mineral on earth. It makes up about 12% of the earth's crust, occurring in a very wide variety of metamorphic, igneous and sedimentary rocks.
Quartz varieties are commonly separated into two groups based on the size of the individual grains or crystals; macrocrystalline quartz in which individual crystals are distinguishable with the naked eye, and cryptocrystalline quartz in which the individual crystals are too small to be easily distinguishable under the light microscope.