Paulrobinsonite

Chemical formula: Ti₈Fe₄O₂

Paulrobinsonite is an extremely rare titanium and iron oxide, forming microscopic, black crystals with a metallic luster.

## Characteristics Paulrobinsonite is an oxide mineral, composed mainly of titanium and iron. It occurs as extremely small, tabular or bladed crystals, rarely exceeding 20 micrometers in length. It typically forms aggregates or appears as single, dispersed crystals within other minerals. It is opaque and has a black color with a metallic luster. ## Physical Properties Due to the microscopic size of the crystals, most physical properties, such as hardness, density, or fracture, have not been precisely determined. The luster is described as metallic, and the streak as black. ## History and Name The mineral was approved by the IMA in 2023. Its name honors Paul Robinson, a retired professor from Dalhousie University in Canada, for his contributions to research on the mineralogy and petrology of metamorphic rocks, including those from Greenland, where the discovery was made.

Properties

Luster: Metallic
Streak: Black
Transparency: Opaque
Crystal system: Trigonal

Diagnostic features

## Identification Identification of paulrobinsonite is impossible without advanced analytical techniques. It requires the use of a scanning electron microscope (SEM) with chemical composition analysis (EDS) and X-ray diffraction (XRD) to confirm the crystal structure and composition. Visually, under high magnification, black, metallic-lustered, tabular crystals can be observed. ## Distinguishing from Similar Minerals It can be confused with other black, opaque oxide minerals occurring in the same environment, such as ilmenite, rutile, or hematite. Definitive differentiation is possible only through chemical and structural analysis. ## Crystal Forms It forms very small, thin, tabular or bladed crystals, often with a hexagonal outline. They occur as single, isolated crystals or small aggregates on the surface of other minerals.

Geological environment

## Genesis Paulrobinsonite forms under conditions of high-grade metamorphism. It was discovered in amphibolite rocks that underwent metamorphism under amphibolite to granulite facies conditions. Its presence is associated with metasomatic and oxidizing processes occurring at high temperatures. ## Mineral Associations It co-occurs with minerals such as rutile, ilmenite, spinels (hercynite), hornblende, plagioclase, sillimanite, corundum, and phlogopite. ## Localities The only confirmed locality worldwide (type locality) is the Akulleq area on the southwest coast of Greenland.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" mineral of purely scientific and systematic value, its main quality criterion is confirmation of identity through analysis. The attractiveness of a specimen is enhanced by the abundance of microcrystals on the rock matrix and their distinct development, visible under high magnification. Association with other rare minerals also increases its scientific value.

Care and storage

## Cleaning Due to its extreme rarity and microscopic size, paulrobinsonite specimens are not subject to cleaning in the traditional sense. Any attempts to clean the host rock should be conducted with the utmost care, preferably under a microscope, using only compressed air to remove dust. ## What to Avoid Contact with any chemicals, ultrasonics, and mechanical cleaning (e.g., brushes) should be avoided, as these could irreversibly damage or remove the microscopic crystals from the substrate. ## Storage Specimens should be stored under stable conditions, in sealed "micromount" containers, to protect them from dust, moisture, and mechanical damage. Vibrations and shocks should be avoided.

Sources

IMA Mineral List (CNMNC)