Elliottite

Chemical formula: NaMgAl<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>F<sub>6</sub>·9H<sub>2</sub>O

Elliottite is a hydrated, fluorinated sodium, magnesium, and aluminum phosphate, forming tiny, colorless, platy crystals.

## Characteristics Elliottite is a mineral from the phosphate group, first described in 2023. It occurs as very small, colorless, platy crystals, reaching sizes up to 150 micrometers. The crystals are transparent and have a vitreous luster. Due to the small size of the crystals, most physical properties are difficult to observe without specialized equipment. ## Physical Properties Elliottite crystals are too small to determine their Mohs hardness or density by standard methods. The density was calculated based on crystallographic data and is 2.30 g/cm³. The mineral is characterized by a vitreous luster and a white streak. It is transparent. ## Colors and Varieties Elliottite is colorless. No colored varieties are known. ## History and Name The mineral is named in honor of Peter Elliott, an Australian mineralogist from the South Australian Museum, for his contributions to phosphate mineralogy. The mineral was approved by the International Mineralogical Association (IMA) in 2022 (IMA2022-043), and its description was published in 2023. It was discovered in samples from the historic Iron Monarch iron mine in South Australia. ## Uses Elliottite has no commercial or industrial applications. It is a mineral of purely scientific and collector's interest, sought after by micromineral specialists.

Properties

Luster
Vitreous
Streak
White
Density
2.30
Cleavage
Perfect on {0001}
Transparency
Transparent
Crystal system
Trigonal

Diagnostic features

## Identification Identification of elliottite is only possible using advanced analytical techniques, such as Raman spectroscopy and X-ray diffraction (XRD), due to the microscopic size of the crystals and their occurrence in complex parageneses. Visually, under magnification, they appear as tiny, colorless, hexagonal plates. ## Distinguishing from Similar Minerals It can be confused with other secondary phosphate minerals found in the same locality, such as fluellite, wavellite, or wardite. Definitive differentiation requires chemical analysis (EDS/WDS) to confirm its unique composition containing sodium, magnesium, aluminum, and fluorine simultaneously. ## Crystal Forms Elliottite forms thin, hexagonal, platy crystals. They occur as single, isolated crystals or loose aggregates on the surface of the host rock.

Geological environment

## Genesis Elliottite is a secondary mineral that formed as a result of hydrothermal processes in the late stage of mineralization, within iron deposits rich in phosphorus. Its formation is associated with the interaction of solutions rich in phosphorus, fluorine, sodium, and magnesium with aluminum-bearing rocks. ## Mineral Associations This mineral co-occurs with other secondary phosphates. In its type locality (Iron Monarch mine), it was found in association with fluellite, wavellite, wardite, strengite, viitaniemiite, and minyulite. ## Localities The only confirmed occurrence of elliottite in the world is its type locality – the Iron Monarch iron mine, located in the Middleback Range region, on the Eyre Peninsula in South Australia.

Rarity

Extremely rare

For collectors

## Quality Criteria As a micromineral, elliottite is primarily evaluated based on the quality and size of its crystals, which in this case means specimens with sharply terminated, well-formed hexagonal plates that are visible under a microscope. The most desirable specimens are those where the crystals are clearly isolated against a contrasting background of the host rock. The presence of associated minerals, such as intensely colored strengite, can enhance the visual appeal of the specimen. ## Popular Localities The only source of elliottite specimens is the Iron Monarch mine in South Australia. Specimens from this locality are extremely rare and sought after by specialized micromineral collectors.

Care and storage

## Cleaning Due to the extreme fragility and small size of the crystals, mechanical cleaning is not recommended and can lead to the destruction of the specimen. If absolutely necessary, the specimen can be carefully rinsed in distilled water and then left to dry completely without the use of heat. ## What to Avoid Avoid contact with any chemicals, acids, and detergents. The mineral is sensitive to changes in temperature and humidity. Do not heat it or expose it to direct sunlight. Avoid ultrasonics and vibrations. ## Storage Elliottite specimens should be stored in stable conditions, in closed "micromount" boxes, protected from dust, shocks, and humidity changes. It is best to store them in a dry place with a constant temperature.

Sources

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