Idrialite Locality: Skaggs Springs Mine, Skaggs Springs, Sonoma County , California , USA ( Locality at mindat.org ) Size: 6.3 x 4.1 x 1.8 cm. Idrialite (named for the Idria Mine in Slovenia, the type locality) is a VERY RARE mineral of organic origin (hydrocarbon). The species is also known as curtisite, which was described from the Skaggs Springs Mine. It has been found in very few localities worldwide. Specimens rarely appear on the market. This is about as good as they get - the mineral does not form eye-visible crystals. Ex. Carlton Davis Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Idrialite
A rare hydrocarbon mineral forming soft greenish-yellow orthorhombic crystals that fluoresce blue.
Intro adapted from Wikipedia (CC BY-SA).
Idrialite is an IMA-recognized mineral species in the organic mineral class, with the chemical formula C₂₂H₁₄.
It crystallizes in the orthorhombic crystal system.
Key properties: Mohs hardness 1–1.5; specific gravity 1.22–1.24; Vitreous to adamantine luster; optically biaxial.
IMA symbol Id, grandfathered status — known before the IMA’s founding, named in 1832.
Probably formed by pyrolysis of organic material near hot springs or by hydrothermal fluids.
It is found associated with Cinnabar, pyrite, gypsum, quartz, “clay” (Idrija mine, Slovenia); metacinnabar, realgar, “opal” (Skaggs Springs, California, USA).
The name refers to the Idrija (Idria) mine, Slovenia, from which the first specimens were collected.