Wangyanite

Chemical formula: PdNi<sub>₈</sub>S<sub>₈</sub>

Wangyanite is a very rare nickel and palladium sulfide, forming tiny, metallic grains in ultramafic rocks.

## Characteristics Wangyanite is an extremely rare mineral from the sulfide group. It occurs as very fine, anhedral (irregularly shaped) grains, usually not exceeding 100 micrometers in size. Due to its size and mode of occurrence, its visual characteristics cannot be assessed with the naked eye. When observed under a microscope in reflected light, it has a creamy-yellow color. ## Physical Properties As a metallic mineral, wangyanite is characterized by a strong, metallic luster and is opaque. Its hardness and other physical properties, such as density, have not been precisely measured due to the small size and rarity of natural grains. Its microhardness (VHN) is approximately 415 kg/mm², suggesting a Mohs hardness in the range of 4-5. ## History and Name The mineral was approved by the IMA in 2018. Its name honors Professor Wang Yan, a Chinese geologist, for her contributions to research on nickel and copper deposits in China. It was discovered in samples from the Yangliuping nickel-copper deposit in Sichuan Province, China. ## Uses Wangyanite has no commercial or industrial applications. Its significance is purely scientific and as a collector's item, being a unique and newly discovered component of certain sulfide deposits.

Properties

Mohs hardness: 4-5
Luster: Metallic
Streak: Black
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Cubic

Diagnostic features

## Identification Identification of wangyanite is impossible without advanced laboratory techniques. It requires analysis under a reflected light microscope (ore microscope), where it appears as creamy-yellow, anisotropic grains. Final confirmation requires chemical composition analysis using an electron microprobe (EDS/WDS) and X-ray diffraction to determine the crystal structure. ## Distinguishing from Similar Minerals Under the microscope, it can be confused with other nickel and palladium sulfides, such as pentlandite, heazlewoodite, or palladseite. Differentiation relies solely on precise chemical composition analysis, especially the nickel to palladium ratio, and crystallographic data. ## Crystal Forms Wangyanite forms exclusively anhedral (irregularly shaped), rounded grains, often occurring as inclusions in other minerals, mainly in pentlandite.

Geological environment

## Genesis Wangyanite forms as a result of magmatic processes in magma chambers of ultramafic rocks. It crystallizes from late, sulfur-rich and platinum-group element (PGE)-rich sulfide melts that separated from the main silicate magma. It is a late-magmatic phase mineral. ## Mineral Associations This mineral occurs in close association with other sulfides. It is most commonly accompanied by pentlandite (in which it often forms inclusions), chalcopyrite, pyrrhotite, and other rarer platinum-group minerals, such as palladseite. ## Localities The only confirmed occurrence (type locality) is the Yangliuping nickel-copper deposit, in the Mianning autonomous region, Sichuan Province in southwestern China.

Rarity

Extremely rare

For collectors

## Quality Criteria Since wangyanite is a microscopic mineral, there are no typical visual quality criteria. The value of a specimen lies in the confirmed presence of the mineral in the host rock (matrix). The most valuable samples are from the type locality, with the richest sulfide mineralization, in which wangyanite has been identified and analytically documented. The specimen has purely scientific value and is for specialized collectors of rare minerals or "micromounts."

Care and storage

## Cleaning Specimens containing wangyanite, due to the microscopic size of the grains, do not require and should not be subjected to cleaning. Any attempts at mechanical or chemical cleaning of the host rock may destroy or remove the fine mineral grains. ## What to Avoid Avoid contact with chemicals, acids, and ultrasound. The specimen should not be heated. The host rock should be protected from moisture to prevent the oxidation of co-occurring sulfides, which could also destroy wangyanite over time. ## Storage Specimens should be stored in stable, dry conditions, preferably in a closed collector's box, to protect them from dust and contaminants. Due to the microscopic nature of the mineral, a label with precise location and identification is crucial.

Sources

IMA Mineral List (CNMNC)