Kalgoorlieite

Chemical formula: As<sub>2</sub>Te<sub>3</sub>

A discredited mineral name, originally described as arsenic telluride (As₂Te₃), but actually a mixture of other minerals.

## Characteristics Kalgoorlieite is not a recognized mineral species. This name refers to material originally found in the gold mines of Kalgoorlie, Western Australia. Studies have shown that the supposed new mineral was in fact a fine-grained mixture of other, already known minerals, most commonly coloradoite (HgTe) and arsenopyrite (FeAsS), as well as other tellurides. ## Physical Properties Since kalgoorlieite is not a single mineral but a mixture, it cannot be assigned constant physical properties. The properties of the described samples, such as hardness, density, or luster, were a resultant of the properties of the constituent minerals and depended on their proportions in the mixture. ## Colors and Varieties Not applicable, as it is not a distinct mineral. The described material typically had a tin-white to steel-gray color with a metallic luster, which corresponds to the appearance of mixtures of tellurides and sulfides. ## History and Name The name "kalgoorlieite" was given in reference to its discovery locality – the famous gold and telluride mining district of Kalgoorlie in Australia. The material was described in the late 19th century as a new arsenic telluride with the formula As₂Te₃. However, later, more advanced analyses, including electron microprobe studies, unequivocally showed that it is a mixture. As a result, the International Mineralogical Association (IMA) officially discredited this name, and it is no longer recognized in mineral systematics.

Properties

rruff id
1c02e602d8c1e7598d7de3876bf2
ima number
IMA2015-119
ima status
approved
type locality
Australia
year approved
2015

Diagnostic features

## Identification Modern diagnostics (e.g., X-ray diffraction (XRD) analysis or micro-area chemical analysis (EDS/WDS)) is the only method to determine that a given material is not a homogeneous phase but a mixture of minerals. Visual identification is impossible. ## Distinguishing from Similar Minerals Kalgoorlieite, as a historical name, refers to material that macroscopically may resemble other massive, metallic tellurides or sulfides, such as altaite, hessite, or arsenopyrite. Definitive differentiation requires chemical and structural analysis, which will show that it is a mixture, not a single mineral. ## Crystal Forms It does not form crystals, as it is a mixture. It occurred in the form of massive, fine-grained aggregates embedded in quartz or other minerals.

Geological environment

## Genesis The material referred to as kalgoorlieite originated from low-temperature, hydrothermal quartz-carbonate veins rich in gold and tellurides, characteristic of the Kalgoorlie deposit. ## Mineral Associations It co-occurred with native gold, calaverite, krennerite, coloradoite, petzite, arsenopyrite, pyrite, and quartz. ## Localities The only known locality from which material called kalgoorlieite was described is the Kalgoorlie-Boulder mining region in Western Australia.

Rarity

Extremely rare

For collectors

## Quality Criteria Specimens have only historical value as an example of a discredited mineral. The collector's value may be enhanced by the presence of visible gold or well-formed crystals of other co-occurring tellurides on the same sample. ## Popular Localities Historical specimens, erroneously described as kalgoorlieite, come exclusively from mines in the Kalgoorlie region of Australia.

Care and storage

## Cleaning Cleaning is not recommended to avoid damaging the delicate structure of the mixture. Any historical specimens can only be gently dusted with a soft brush. ## What to Avoid Avoid contact with water, acids, and other chemicals that could react with the components of the mixture (tellurides and sulfides). The material is brittle and susceptible to mechanical damage. ## Storage Store in a dry place, preferably in a closed display box, to prevent oxidation and crumbling of the sample.

External references

Sources

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