Hoelite

Hoelite is a mineral, discovered in 1922 at Mt. Pyramide, Spitsbergen, Norway and named after Norwegian geologist Adolf Hoel (1879–1964). Its chemical formula is C₁₄H₈O₂ (9,10-anthraquinone).^[2]

Hoelite
Yellow acicular crystals of hoelite (picture size: 10 mm)
General
Category	Organic mineral
Formula	C14H8O2
IMA symbol	Hoe[1]
Strunz classification	10.CA.15
Dana classification	50.4.2.1
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/a
Unit cell	a = 15.81 Å, b = 3.967 Å c = 7.876 Å; β = 102.67°; Z = 2
Identification
Color	Yellow, yellowish green
Crystal habit	Acicular clusters; pseudo-orthorhombic
Cleavage	Good
Streak	Light yellow
Diaphaneity	Semitransparent
Specific gravity	1.42
Optical properties	Biaxial (+)
Refractive index	nα≈1.75, nβ≈1.75, nγ≈2.0
References	[2][3]

It is a very rare organic mineral which occurs in coal fire environments in association with sal ammoniac and native sulfur.^[2]