Proxitwelvefoldite

Chemical formula: Pd₃Ni₄Te₈

Proxitwelvefoldite is an extremely rare palladium-nickel telluride, discovered in Western Australia, occurring as microscopic inclusions in other minerals.

## Characteristics Proxitwelvefoldite is a palladium-nickel telluride with the chemical formula Pd₃Ni₄Te₈. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2022. It occurs as extremely small, anhedral (lacking crystal faces) grains, reaching sizes up to 15 micrometers. These grains are most commonly found as inclusions within calgoorlite crystals. Due to its microscopic size, visual features observable with the naked eye are not possible to observe. ## Physical Properties Due to the extreme rarity and microscopic size of the grains, most physical properties of proxitwelvefoldite have not yet been determined. Hardness, density, luster, and transparency remain unknown. In reflected light (under a ore microscope), the mineral has a gray color with a creamy tint and exhibits weak pleochroism. ## History and Name The name "proxitwelvefoldite" refers to its chemical composition and crystal structure, which is similar to a twelve-fold quasicrystalline phase. It was discovered in material originating from historical gold mines in the Kalgoorlie-Boulder region of Western Australia. It was described by a team of scientists led by Luca Bindi in 2023.

Properties

Crystal system
Tetragonal

Diagnostic features

## Identification Identification of proxitwelvefoldite is possible only using advanced laboratory techniques. It requires analysis in reflected light under a polarizing microscope and confirmation of its chemical composition using an electron microprobe (EMPA) and crystal structure by X-ray diffraction (XRD). ## Distinguishing from similar minerals This mineral occurs in paragenesis with other similar tellurides, such as calgoorlite, coloradoite, or krennerite. Distinguishing it from them relies solely on precise chemical analysis and crystallographic data. ## Crystal forms So far, it has only been observed in the form of anhedral, microscopic grains.

Geological environment

## Genesis Proxitwelvefoldite forms as a result of hydrothermal processes associated with gold mineralization. It crystallizes at relatively low temperatures from solutions rich in tellurium, palladium, and nickel. ## Mineral associations This mineral has been found as inclusions in calgoorlite (Au₂Te). It co-occurs with other tellurides, such as coloradoite (HgTe), krennerite (AuTe₂), petzite (Ag₃AuTe₂), and native gold (Au). ## Localities The only confirmed locality of proxitwelvefoldite in the world is its type locality – historical gold deposits in the Kalgoorlie-Boulder region, Kalgoorlie-Boulder Shire, Western Australia.

Rarity

Extremely rare

For collectors

## Quality criteria As a mineral of purely scientific significance, it is not subject to classic collector's evaluation criteria. The value of a specimen lies solely in the confirmed presence of proxitwelvefoldite, documented by appropriate analyses. Such specimens are found almost exclusively in research institutions and university museums.

Care and storage

## Cleaning Due to its microscopic nature and occurrence as inclusions in other minerals, cleaning individual proxitwelvefoldite grains is not practiced. The host specimen (e.g., calgoorlite) should be cleaned with utmost care, using only compressed air to remove dust. ## What to avoid Avoid all mechanical cleaning methods (brushes, ultrasonics) and chemical cleaning, as they can irreversibly damage or destroy the microscopic mineral grains and the host rock. ## Storage Specimens containing proxitwelvefoldite are extremely valuable research materials. They should be stored under stable conditions, in specialized containers (e.g., membrane boxes), protected from shocks, dust, and humidity changes.

External references

Sources

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