Abelsonite, a crystalline nickel porphyrin with the probable composition C31H32N4Ni, has been found in eight drill cores in or near the Mahogany Zone oil shale of the Green River Formation in Uintah County, Utah. Associated authigenic minerals include orthoclase, pyrite, quartz, dolomite, analcime, and a K-Fe micaceous mineral. Abelsonite occurs as aggregates of platy crystals, as much as 3 mm long, that range in color from pink-purple to dark reddish-brown. The crystals are very soft (<3 on Mohs scale) and have a semimetallic to adamantine luster. Probable cleavage is (111). In transmitted light the color is red or reddish-brown, with intense absorption to reddish-brown. Its reaction with high-index liquids and its strong absorption prevented determination of optical characteristics. Abelsonite is triclinic, space-group aspect P*, with cell dimensions (Weissenberg), a = 8.44, b = 11.12, с = 7.28А, α = 90°53’ β = 113°45’, γ = 79°34’; volume 613.8A3, calculated density (for Z = 1) = 1.45 g/cm3 The five strongest lines of the X-ray powder pattern (d value in relative intensity, indices) are 10.9 (100) 010, 3.77 (80) 111, 7.63 (50) 100, 5.79 (40) 110, 3.14 (40) 012. Ultraviolet, visible, and infrared spectra indicate that abelsonite is a deoxophylloerythroetio-porphyrin, presumably a chlorophyll derivative. The mineral is named in honor of Philip H. Abelson, President, Carnegie Institution of Washington.

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