Sulfopadmaite

Chemical formula: PdBiS

Sulfopadmaite is a very rare palladium bismuth sulfide, forming microscopic, metallic grains in ultramafic rocks.

## Characteristics Sulfopadmaite is an extremely rare sulfide mineral, composed of palladium, bismuth, and sulfur. It occurs as very small, anhedral (irregularly shaped) grains, typically not exceeding a few tens of micrometers in size. It is observed exclusively in polished sections under a microscope, where it appears as isotropic, creamy-white inclusions within other minerals. ## Physical Properties Due to the microscopic size of the crystals, most physical properties, such as hardness, density, or luster, have not been precisely measured, but only estimated based on comparisons with other platinum-group metal sulfides. The luster is metallic. ## History and Name The mineral was approved by IMA in 2021 (IMA2021-003). Its name refers to its similarity to padmaite (PdBiSe), with which it forms a series, and to the dominance of sulfur (Latin: *sulphur*) in its chemical composition. It was discovered in material from the Padma intrusion, within the Oulanka massif in Karelia, Russia.

Properties

Luster
Metallic
Transparency
Opaque
Crystal system
Cubic

Diagnostic features

## Identification Identification of sulfopadmaite is possible only through advanced laboratory techniques. In reflected light (under an ore microscope), it is creamy-white and isotropic. Final confirmation requires chemical composition analysis by electron microprobe (EDS/WDS) and X-ray diffraction (XRD) studies to determine the crystal structure. ## Distinguishing from similar minerals It can be confused with other palladium and bismuth sulfides and selenides, such as padmaite (PdBiSe) or froodite (PdBi₂). Differentiation relies solely on precise analysis of the sulfur to selenium and bismuth ratio in the chemical composition.

Geological environment

## Genesis Sulfopadmaite forms as a result of hydrothermal processes in the late stages of magmatic crystallization, within differentiated ultramafic and mafic intrusions. It forms in zones enriched in platinum-group elements (PGE). ## Mineral associations This mineral co-occurs with other PGE minerals, such as froodite, kotulskite, isomertieite, as well as with chalcopyrite, pentlandite, bornite, and magnetite. ## Localities The only confirmed occurrence (type locality) is the Padma intrusion within the Oulanka gabbro-peridotite massif, located in the Republic of Karelia, Russia.

Rarity

Extremely rare

For collectors

## Quality criteria Sulfopadmaite does not occur as collector specimens in the traditional sense of the word. Its value is purely scientific. The only form in which it might enter specialized institutional collections are polished rock sections with precisely studied and identified microscopic grains.

Care and storage

## Cleaning Due to its extreme rarity and microscopic size, sulfopadmaite specimens are not subject to cleaning in the amateur sense. Any operations on research material (polished sections) require specialized laboratory equipment. ## What to avoid Avoid any chemicals, ultrasonics, or mechanical cleaning, which could destroy or scratch the surface of the polished section containing the microscopic mineral grains. ## Storage Specimens (sections) should be stored in dry conditions, in specialized boxes protecting them from dust and mechanical damage.

Sources

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