Abelsonite

Abelsonite is a nickel porphyrin mineral with formula  C 31 H 32 N 4 Ni. It was discovered in 1969 in the U.S. State of Utah and described in 1975. The mineral is named after geochemist Philip H. Abelson. It is the only known crystalline geoporphyrin.

Description
Abelsonite is semitransparent and pink-purple, dark greyish purple, pale purplish red, or reddish brown in color. The mineral occurs as thin laths or plates or small aggregates up to 1 cm (0.39 in). The mineral is soluble in benzene and acetone and is insoluble in water, dilute hydrochloric acid, and dilute nitric acid.

Occurrence and formation
The mineral is known only from the Parachute Creek Member of the Green River Formation. It has been known from the Uinta Basin in Utah since its discovery and from the Piceance Basin in Colorado since 1985. Abelsonite occurs in association with albite, analcime, dolomite, mica, orthoclase, pyrite, and quartz. Abelsonite is a secondary mineral that formed in fractures, vugs, and bedding planes of oil shale. The mineral probably formed from diagenesis of chlorophyll, likely chlorophyll a, which was transported as an aqueous solution into a favorable geologic setting. In 2003, abelsonite was fully synthesized for the first time.

Structure
As of 1989, abelsonite was the only the known geoporphyrin to have a crystalline structure. Most geoporphyrins occur as a series of homologues spanning a large range of carbon numbers. The porphyrin which comprises abelsonite is common, but it does not usually occur in isolation from other porphyrins. The mineral is a deoxophylloerythroetioporphyrin (DPEP), with nickel occupying the center of the porphyrin ring. Most of the mineral consists of a C31 porphyrin with small quantities of a C30 norisomer. The mineral crystallizes in the triclinic crystal system.