Ferhodsite

Chemical formula: (Fe,Rh,Ni,Ir,Cu,Co,Pt)<sub>9-x</sub>S<sub>8</sub>

Ferhodsite is an extremely rare iron and rhodium sulfide, occurring as microscopic, metallic grains in ultramafic rocks.

## Characteristics Ferhodsite is a very rare sulfide mineral, identified based on microscopic, irregular grains with a metallic appearance. Its size typically does not exceed several tens of micrometers. Under a polarizing microscope in reflected light, it exhibits a creamy-white color with a pinkish tint. ## Physical Properties Due to the microscopic size of the grains, most physical properties, such as hardness, density, cleavage, or fracture, have not been precisely determined. The mineral is characterized by a metallic luster and is opaque. ## History and Name The name Ferhodsite refers to its chemical composition – the dominance of iron (Latin: *ferrum*) and rhodium (*rhodium*). The mineral was first described in 1997 by N. S. Rudashevsky, J. P. Kim, A. G. Mochtalov, and J. A. Budko based on material from the Kondyor Massif in Khabarovsk Krai, Russia.

Properties

Luster
Metallic
Cleavage
None
Transparency
Opaque
Crystal system
Cubic

Diagnostic features

## Identification Identification of ferhodsite is possible only through advanced laboratory techniques, such as reflected light ore microscopy and chemical analysis using an electron microprobe (EDS/WDS). A characteristic feature is its unique chemical composition with a dominance of iron and rhodium. ## Distinguishing from Similar Minerals It can be confused with other microscopic platinum-group metal (PGM) sulfides, such as cuproiridsite, cuprorhodsite, or malanite. Differentiation requires precise chemical analysis. ## Crystal Forms Ferhodsite occurs as anhedral (irregular), irregular grains, often forming aggregates or intergrowths with other platinum-group minerals.

Geological environment

## Genesis Ferhodsite forms as a result of magmatic processes within ultramafic rocks, particularly in dunites and pyroxenites. It forms in platinum-group element (PGE) deposits associated with layered complexes or Uralo-Alaskan type massifs. ## Mineral Associations This mineral co-occurs with other platinum-group minerals, such as native platinum and osmium, as well as with sulfides (laurite, erlichmanite, cuproiridsite, cuprorhodsite) and chromite. ## Localities The only confirmed occurrence of ferhodsite in the world is the Kondyor (Konder) Massif in Khabarovsk Krai, Russian Far East.

Rarity

Extremely rare

For collectors

## Quality Criteria Ferhodsite does not occur in macroscopic specimens, therefore it is not traded on the collector's market in the traditional sense. Its value is purely scientific. Any host rock specimens (dunites) with confirmed presence of ferhodsite may be valuable for specialized institutional and research collections.

Care and storage

## Cleaning Specimens containing ferhodsite, due to their microscopic nature and embedding in the host rock, do not require and should not undergo chemical or mechanical cleaning. ## What to Avoid Contact with acids and other aggressive chemicals should be avoided, as they could damage both the mineral itself and the host rock. There are no specific recommendations regarding light or temperature, but standard protection against extreme conditions is advisable. ## Storage Rock samples with ferhodsite should be stored under stable conditions, in sealed containers or display cases, to protect them from dust and mechanical damage.

Sources

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