Elkinstantonite

Chemical formula: Fe₂+₄(PO₄)₂O

Elkinstantonite is an extremely rare iron phosphate, discovered in the El Ali meteorite, distinguished by its occurrence exclusively in extraterrestrial matter.

## Characteristics Elkinstantonite is an iron phosphate mineral, identified as a natural material only in 2022. Its grains are typically small, not exceeding 100 micrometers in size, and occur as inclusions within an iron meteorite. Visually, in reflected light, it has a grayish color and a metallic luster. Due to the microscopic size of its crystals, its macroscopic features are not fully understood. ## Physical Properties The mineral is characterized by a Mohs hardness of 5.5. It has a relatively high density, calculated at 4.62 g/cm³. It exhibits a metallic luster. It is an opaque mineral. ## History and Name The mineral's name honors Lindy Elkins-Tanton, an American planetary scientist and principal investigator of NASA's Psyche mission, which aims to study a metallic asteroid. Elkinstantonite was officially approved by the International Mineralogical Association (IMA) in 2022 after its discovery in the 15-ton El Ali meteorite, found in Somalia. The mineral was identified by scientists from the University of Alberta during the analysis of a fragment of this meteorite.

Properties

Mohs hardness: 5.5
Luster: Metallic
Streak: Not determined
Density: 4.62
Cleavage: Not determined
Fracture: Not determined
Transparency: Opaque
Crystal system: Orthorhombic

Diagnostic features

## Identification Identification of elkinstantonite is possible only through advanced laboratory techniques, such as electron microprobe (for chemical composition analysis) and X-ray diffraction (for determining crystal structure). In reflected light under a microscope, it is visible as grayish, metallic-lustered inclusions within the meteorite. ## Differentiation from similar minerals Elkinstantonite co-occurs with another newly discovered phosphate, elaliite, as well as with troilite and graphite in the kamacite matrix. Distinguishing it from these minerals requires specialized instrumental analysis. Its unique chemical composition and crystallographic structure are key diagnostic features. ## Crystal forms The mineral forms subhedral (partially developed) to anhedral (undeveloped) grains and aggregates of microscopic size, typically below 100 µm.

Geological environment

## Genesis Elkinstantonite formed under conditions prevailing within the parent body of the IAB iron meteorite. It is believed to be a product of metasomatic processes or crystallization from a trapped phosphorus-rich melt that reacted with the surrounding iron (kamacite) during very slow cooling within the asteroid. ## Mineral associations This mineral occurs in close association with kamacite (the main component of the meteorite), troilite, graphite, and elaliite – another iron phosphate discovered in the same meteorite. ## Localities The only confirmed locality of elkinstantonite on Earth is the El Ali meteorite, found in the Hiiraan region of Somalia. This is its type locality.

Rarity

Extremely rare

For collectors

## Quality criteria As a newly discovered mineral available only as microscopic inclusions in a single meteorite, elkinstantonite is not an item of collector trade in the form of isolated specimens. Collectible value is held by fragments of the El Ali meteorite in which the presence of this mineral has been confirmed. In such cases, the value is determined by the size and quality of the meteorite fragment itself and the documented presence of mineral phases, including elkinstantonite.

Care and storage

## Cleaning Due to its extreme rarity and occurrence as microscopic inclusions within the meteorite matrix, isolated grains of elkinstantonite are not subject to cleaning. Any interventions on a meteorite fragment containing this mineral should be performed exclusively by specialized laboratories. ## What to avoid Specimens of the El Ali meteorite containing elkinstantonite should be protected from moisture, which could cause corrosion of the surrounding iron (kamacite). Contact with chemicals, acids, and extreme temperature changes should be avoided. Attempts to independently extract the mineral from the matrix should not be made. ## Storage Meteorite fragments should be stored under stable conditions, preferably in a dry environment, e.g., in a sealed container with a desiccant. Display should be in a closed cabinet, away from direct sunlight and heat sources.