Padmaite

Chemical formula: PdBiSe

Padmaite is a rare palladium bismuth selenide, forming tiny, metallic inclusions in other minerals.

## Characteristics Padmaite is an extremely rare mineral from the sulfide group, specifically a palladium bismuth selenide. It occurs as very small, anhedral (not exhibiting its own crystallographic forms) grains, usually not exceeding 100 micrometers in size. Most often, it forms inclusions within the mineral sobolevskite or occurs at its boundaries. It has a metallic appearance and a creamy-white color in reflected light. ## Physical Properties Due to the extremely small size of the grains, most of padmaite's physical properties have not been precisely determined. The mineral is opaque and has a metallic luster. Its hardness and density have not been measured, but only theoretically calculated. ## History and Name The mineral's name comes from its discovery locality – the Padma River, flowing through a nickel-copper deposit in Karelia, Russia. It was described and approved as a new mineral by the International Mineralogical Association (IMA) in 1997. The discoverers were Y.A. Pakhomovskii, A.P. Krivenko, L.I. Polezhaeva, E.M. Spiridonov, V.V. Ermilov, and S.F. Sluzhenikin.

Properties

Mohs hardness
3-4
Color
Light yellow
Luster
Metallic
Density
0
Cleavage
Imperfect cleavage in two perpendicular directions.
Transparency
Opaque
Crystal system
Isometric

Diagnostic features

## Identification Identification of padmaite is possible only through advanced laboratory techniques, such as ore microscopy in reflected light and chemical analysis using an electron microprobe (EDS/WDS). In reflected light, it exhibits a creamy-white color and weak anisotropy. ## Distinguishing from Similar Minerals It can be confused with other rare selenides and tellurides of platinum-group metals, such as sobolevskite (PdBi), kotulskite (Pd(Te,Bi)), or polarite (Pd(Bi,Pb)). Differentiation requires precise chemical composition analysis, as all these minerals have a similar appearance and co-occur. ## Crystal Forms Padmaite forms exclusively anhedral, irregular grains and aggregates. No well-formed crystals have been observed.

Geological environment

## Genesis Padmaite forms as a result of hydrothermal processes in ultramafic and mafic magmatic intrusions, where platinum-group elements (PGE), copper, and nickel are concentrated. It crystallizes in the late stages of sulfide deposit formation. ## Mineral Associations This mineral co-occurs with other PGE minerals, mainly sobolevskite, polarite, kotulskite, sperrylite, as well as chalcopyrite, pentlandite, cubanite, and magnetite. ## Localities The main and type locality for padmaite is the copper-nickel deposit in the Padma River region of Karelia, Russia. It has also been identified in other PGE deposits worldwide, including the Bushveld Complex in South Africa and the Lac des Iles deposit in Ontario, Canada.

Rarity

Extremely rare

For collectors

## Quality Criteria Padmaite specimens are of scientific value only and for highly specialized collectors of systematic minerals. Due to its microscopic nature, its aesthetic qualities are nil. The value of a specimen lies in the confirmed presence of the mineral in the host rock, documented by analyses. The most valuable samples are from the type locality (Karelia), containing rich associations of other rare PGE minerals.

Care and storage

## Cleaning Due to its microscopic size and occurrence as inclusions within the host rock, individual padmaite grains are not subject to cleaning. The host specimen can be mechanically cleaned using a soft brush and distilled water, taking care not to damage the delicate surface. ## What to Avoid Avoid contact with strong acids and chemicals that could react with the mineral or associated minerals. The specimen should not be subjected to ultrasonic cleaning. ## Storage Specimens containing padmaite should be stored under stable conditions, away from dust and moisture, preferably in a closed display box, to prevent mechanical damage.

External references

Sources

Read more