Palarstanide
Chemical formula: Pd₅(Sn,As)₂
Palarstanite is a rare mineral from the group of palladium, tin, and arsenic alloys, forming tiny, metallic grains in ultramafic rocks.
Properties
- Mohs hardness
- 5
- Color
- steel-gray
- Luster
- Metallic
- Streak
- Black
- Density
- 0
- Cleavage
- {0001}
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Hexagonal
Diagnostic features
## Identification Identification of palarstanite is impossible without advanced laboratory techniques. Recognition relies on analysis in reflected light (ore microscopy) and chemical analysis using an electron microprobe (EDS/WDS). In reflected light, it has a grayish-white color with a creamy tint and is anisotropic. ## Distinguishing from Similar Minerals It can be confused with other platinum-group minerals (PGMs) such as stannopalladinite, atokite, or rustenburgite, which have a similar appearance in reflected light. Definitive distinction requires chemical composition analysis, which will reveal the characteristic ratio of palladium, tin, and arsenic. ## Crystal Forms Palarstanite forms exclusively anhedral, i.e., irregularly shaped, rounded grains. No well-formed crystals have been observed.
Geological environment
## Genesis Palarstanite forms as a result of magmatic processes within ultramafic and mafic rock intrusions. It crystallizes from late, platinum-group element (PGE)-rich sulfide melts that separated from the main silicate magma. ## Mineral Associations This mineral co-occurs with other platinum-group minerals and sulfides. It is most commonly associated with: rustenburgite, atokite, stibiopalladinite, native platinum, native gold, sperrylite, as well as chalcopyrite, pentlandite, and pyrrhotite. ## Localities The most important and confirmed palarstanite localities worldwide include: - Onverwacht intrusion in Mpumalanga Province (formerly Eastern Transvaal), RSA - type locality. - Bushveld Complex deposits, RSA. - Nickel and copper deposits in the Noril'sk and Talnakh regions of Siberia, Russia. - Duluth Complex intrusion in Minnesota, USA. - Lac des Îles deposit in Ontario, Canada.
Rarity
Very rare
For collectors
## Quality Criteria As a microscopic mineral, palarstanite is not evaluated based on typical collector's criteria such as color, luster, or crystal form visible to the naked eye. The scientific and collector's value of a specimen depends on: - Confirmation of palarstanite's presence through analysis. - Richness of association with other rare platinum-group minerals. - Grain size, although they rarely exceed fractions of a millimeter. - Origin from a classic, well-documented locality. ## Popular Localities Specimens for scientific research and specialized collectors primarily come from the Bushveld Complex in South Africa and the Noril'sk region deposits in Russia.
Care and storage
## Cleaning Due to its extreme rarity and occurrence as microscopic grains embedded in other minerals, palarstanite specimens are not cleaned in the traditional sense. Any cleaning of the host rock should be done mechanically, with great care. ## What to Avoid Avoid contact with strong acids and chemicals that could react with metals and sulfides in the host rock. Specimens should be protected from moisture to prevent oxidation of associated minerals. ## Storage Specimens containing palarstanite, typically in the form of polished sections for microscopic examination or small rock fragments, should be stored in a dry, stable environment, preferably in specialized collector's boxes or micromount containers, to prevent physical damage and dust accumulation.