Abelsonite

Chemical formula: Ni<sup>2+</sup>C<sub>31</sub>H<sub>32</sub>N<sub>4</sub>

Abelsonite is an extremely rare organic mineral, being the only known crystalline nickel porphyrin, valued for its unique chemical composition and intense, purple-pink color.

## Characteristics Abelsonite is a mineral from the group of organic compounds, specifically the only known mineral representative of porphyrins. It occurs as very small, thin, tabular or bladed crystals, which rarely exceed a few millimeters in length. These crystals often form irregular clusters and aggregates. The mineral is characterized by a striking color, from pinkish-purple to dark reddish-brown, and a strong, almost metallic luster. ## Physical Properties It is a very soft mineral, with a Mohs hardness of 2-3, meaning it can be scratched with a fingernail. It has an exceptionally low density, about 1.45 g/cm³, which is typical for organic minerals. It exhibits submetallic to adamantine luster and is transparent to translucent in thin fragments. ## Colors and Varieties The dominant colors of abelsonite are shades of purple and red: from pinkish-purple, through violet-red, to dark reddish-brown. No color or commercial varieties are distinguished. ## History and Name The mineral is named in honor of Philip Hauge Abelson (1913–2004), an American physicist and geochemist, a pioneer in the study of organic matter in rocks. Abelsonite was first described in 1978 based on material obtained from drill cores in the Green River Formation in Utah, USA. ## Uses Abelsonite has no industrial application. Its significance is purely scientific, as a unique example of a naturally crystallizing porphyrin, and collectible, due to its extreme rarity and unique origin.

Properties

Mohs hardness
2-3
Luster
Sub-Metallic
Streak
Pink
Density
1.45
Cleavage
Good on {111}
Fracture
Uneven
Transparency
Transparent to Translucent
Crystal system
Triclinic

Diagnostic features

## Identification The key diagnostic features of abelsonite are its unique purple-pink color, tabular crystal habit, low hardness, and density. However, the most important indicator is its occurrence environment – it occurs almost exclusively in oil shales (kerogen marls) of the Green River Formation. ## Distinguishing from Similar Minerals Due to its color, it could theoretically be confused with erythrite or realgar. However, erythrite forms acicular crystals in the oxidation zones of cobalt and nickel deposits, and realgar is an arsenic sulfide found in low-temperature hydrothermal veins. The geological context (oil shale) and completely different physical properties (abelsonite is much lighter and often forms flakes) allow for easy differentiation. ## Crystal Forms Abelsonite forms very thin, flat crystals with a tabular or bladed habit. They usually occur as single, scattered flakes on the surface of the host rock or form small, loose aggregates and rosettes.

Geological environment

## Genesis Abelsonite is a mineral of diagenetic origin. It formed as a result of the transformation of chlorophyll, derived from cyanobacteria and algae, under anaerobic and saline conditions. This process occurred in organic-rich lake sediments that gave rise to the oil shales of the Green River Formation. The source of nickel necessary for the mineral's formation was probably volcanic ash deposited in the same sedimentary basin. ## Mineral Associations This mineral co-occurs with other authigenic minerals that crystallized within the shales. It is most commonly associated with analcime, dolomite, microcline, pyrite, and quartz. ## Localities The most important and classic locality for abelsonite is the Green River Formation, especially its organic-rich "Mahogany Zone" in Uintah County, Utah, USA. It has also been found in the Piceance Creek Basin in Colorado (USA) and in trace amounts in Kupferschiefer in Germany.

Rarity

Extremely rare

For collectors

## Quality Criteria The most highly prized abelsonite specimens are those that contain numerous, well-formed, and intensely colored crystals on a small rock matrix. Crystal size is a key factor – flakes a few millimeters in size are already considered exceptional. The purity of the specimen and the absence of mechanical damage to the fragile crystals significantly increase its value. ## Popular Localities The vast majority of the best collector specimens come from drill cores obtained from wells in Uintah County, Utah, USA, especially from the historic WOSCO (White River Shale Oil Corporation) well. Specimens from other localities are extremely rare on the market.

Care and storage

## Cleaning Abelsonite specimens are extremely delicate and sensitive. Cleaning should be kept to an absolute minimum. Only gentle dust removal with a soft brush or a stream of compressed air from a safe distance is permissible. Avoid contact with water and any chemical agents. ## What to Avoid The mineral is sensitive to high temperatures, which can damage it. As an organic compound, it can react with organic solvents (alcohol, acetone). It should be protected from prolonged exposure to direct sunlight (UV radiation), which theoretically can cause its intense color to fade. Ultrasonic cleaners or steam cleaners must not be used. ## Storage It is recommended to store specimens in closed, stable conditions, preferably in a "membrane box" or a padded collector's box, to protect the fragile crystals from mechanical damage. Avoid environments with high humidity and sudden temperature changes.

External references

Sources

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