Idrialite

Idrialite
Idrialite, Skaggs Springs Mine, Sonoma County, California (size: 6.3 x 4.1 x 1.8 cm
General
Category	Organic mineral
Formula (repeating unit)	C22H14
Strunz classification	10.BA.20
Dana classification	50.03.08.01
Crystal system	Orthorhombic Unknown space group
Unit cell	a = 8.07, b = 6.42 c = 27.75 [Å]; Z = 4
Identification
Color	Greenish yellow, light brown, colorless
Cleavage	{001}, perfect; {100}, poor
Fracture	Conchoidal
Mohs scale hardness	1.5
Luster	Vitreous to adamantine
Specific gravity	1.236
Optical properties	Biaxial (+)
Refractive index	nα= 1.557 nβ = 1.734 nγ = 2.07
Pleochroism	X = pale yellow; Y = Z = yellow
2V angle	84°
Ultraviolet fluorescence	Short UV=blue, orange, yellow, green white
References

Idrialite, or idrialine, is a soft, orthorhombic hydrocarbon mineral with chemical formula: C₂₂H₁₄. It is usually greenish yellow to light brown in color with bluish fluorescence.

Raman spectroscopy studies indicate that it may be a mixture of complex hydrocarbons including benzonaphthothiophenes (chemical formula: C₁₆H₁₀S) and dinaphthothiophenes (chemical formula: C₂₀H₁₂S).

It was first described in 1832 for an occurrence in the Idrija region west of Ljubljana, northwestern Slovenia. It also occurs at Skaggs Springs, Sonoma County, western Lake County and the Knoxville Mine in Napa County, California. It has also been reported from localities in France, Slovakia and Ukraine.

It can be found mixed with clay, pyrite, quartz and gypsum associated with cinnabar in the Idrija occurrence and with metacinnabar, realgar and opal in the Skaggs Spring location.

Its combustibility gave rise to the term "inflammable cinnabar", which is one of its synonyms.