Zincite is the mineral form of zinc oxide (ZnO). In nature its crystal form is rare, with the exception of Franklin, New Jersey, an area also known for its fluorescent minerals. It has a hexagonal crystal structure and color that depends on impurities. The zincite found in Franklin, New Jersey is red colored (mostly due to iron and manganese) and associated with willemite and franklinite.
Zincite crystals can be grown artificially and synthetic zincite crystals are available as a by-product of zinc smelting. Synthetic crystals can be colorless or range in color from dark red, orange, yellow to light green.
Both natural and synthetic zincite crystals are significant for their early use use as semiconductor crystal detectors in the early development of crystal radios before the advent of vacuum tubes. As an early radio detector it was used in a junction with another mineral, chalcopyrite, and the combination was known as the Perikon detector.