Bowlesite

Chemical formula: PtSnS

Bowlesite is a rare platinum-tin sulfide, occurring as microscopic grains in ultramafic rocks.

## Characteristics Bowlesite is a very rare sulfide mineral, composed of platinum, tin, and sulfur. It occurs as extremely small, rounded or irregular grains, usually not exceeding a few tens of micrometers in size. Due to its size, its visual characteristics can only be observed under high magnification in ore microscopy. When observed in reflected light, it has a creamy white color. ## Physical Properties Due to the microscopic size of the grains, most physical properties, such as hardness, density, luster, or transparency, have not been precisely determined for macroscopic samples. The Vickers hardness (VHN₁₀₀) is 584 kg/mm², which suggests significant hardness. ## History and Name The mineral was named after John F. W. Bowles (born 1946), a British mineralogist, in recognition of his contributions to the study of platinum group minerals. It was approved as a new mineral by the International Mineralogical Association (IMA) in 1980. It was first described based on material from platinum-bearing concentrates from the Merensky Reef in the Bushveld Complex, South Africa. ## Applications Bowlesite has no industrial applications. It is of purely scientific interest and is an object of interest for specialized collectors of platinum group minerals.

Properties

Luster
Metallic
Transparency
Opaque
Crystal system
Orthorhombic

Diagnostic features

## Identification Identification of bowlesite is impossible without advanced laboratory techniques. It requires analysis in reflected light under a polarizing microscope and confirmation of chemical composition using an electron microprobe (EDS/WDS). In reflected light, it is creamy white and exhibits weak anisotropy. ## Distinguishing from Similar Minerals It can be confused with other platinum group sulfides, such as braggite, cooperite, or malanite, with which it often coexists. Differentiation requires precise quantitative analysis of the chemical composition, as all these minerals have a similar appearance in microscopic studies. ## Crystal Forms Bowlesite forms exclusively anhedral (irregularly shaped), rounded grains and inclusions in other minerals, mainly in copper, nickel, and iron sulfides.

Geological environment

## Genesis Bowlesite is a mineral of magmatic origin. It crystallizes in the late stages of solidification of sulfide magma associated with ultramafic and mafic rock intrusions, such as pyroxenites, dunites, or norites. It forms in nickel, copper, and platinum group element sulfide deposits. ## Mineral Associations It most commonly coexists with other platinum group minerals, such as braggite, cooperite, laurite, as well as with base metal sulfides: pentlandite, pyrite, pyrrhotite, and chalcopyrite. Sperrylite and stibiopalladinite may also accompany it. ## Localities The most important and classic localities for this mineral are: - The Bushveld Complex in South Africa (Transvaal), particularly in the Merensky Reef area (type locality). - Ni-Cu-PGE deposits in the Norilsk region and on the Taimyr Peninsula in Russia. - The Stillwater Complex in Montana, USA. - The Sudbury Complex in Ontario, Canada.

Rarity

Very rare

For collectors

## Quality Criteria Due to its microscopic nature, bowlesite specimens are not evaluated according to typical criteria such as crystal size or form. The collector and scientific value of a specimen lies in the richness of the mineral association and in the confirmation of bowlesite's presence through analysis. The most valuable are polished sections with well-documented and identified bowlesite grains in association with other rare platinum group minerals.

Care and storage

## Cleaning Specimens in which bowlesite has been identified are usually polished rock samples (known as polished sections) or fragments of host rocks. Cleaning should be limited to wiping the surface with a soft, dry microfiber cloth to remove dust. Do not use water or any chemical agents. ## What to Avoid Avoid contact with chemicals, acids, and ultrasonic cleaners, which can damage both the mineral itself and the surrounding host rock. Polished surfaces are susceptible to scratches, so they should be protected from contact with harder materials. ## Storage Bowlesite specimens are best stored in stable conditions, in closed collector boxes, to protect them from dust and mechanical damage. Due to the microscopic nature of the mineral, proper labeling of the sample and the location of identified grains is crucial.

Sources

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