Michitoshiite-(Cu)

Chemical formula: Rh(Cu₁-xGex) 0<x<=0.5

Michitoshiite-(Cu) is an extremely rare native metal group mineral, being a natural alloy of rhodium, copper, and germanium.

## Characteristics Michitoshiite-(Cu) is a natural alloy of rhodium, copper, and germanium, belonging to the native metal group. It occurs as extremely small, rounded grains, not exceeding 0.1 mm in size, usually intergrown with other platinum-group minerals. Observed under a microscope in reflected light, it has a creamy-white color with a pinkish hue. ## Physical Properties Due to the extremely small size of the grains, most physical properties, such as hardness, density, luster, or transparency, have not been precisely determined. It is an opaque mineral with a metallic luster. ## History and Name The mineral was approved by the IMA in 2017 (IMA2017-056). Its name honors Dr. Michitoshi Miyahara (born 1980), a Japanese mineralogist and planetologist from Hiroshima University, for his contributions to the study of extraterrestrial minerals. The suffix -(Cu) in the name indicates copper as the dominant component in one of the structural positions, according to the nomenclature of isostructural minerals with native copper.

Properties

Mohs hardness
5-0
Color
silver-gray color
Luster
Metallic
Density
10.78
Transparency
Opaque
Crystal system
Isometric

Diagnostic features

## Identification Identification of michitoshiite-(Cu) is possible only through advanced laboratory techniques, such as electron microprobe analysis (EMPA) in reflected light. Its characteristic feature is its chemical composition – an alloy of rhodium, copper, and germanium. Visually, under a microscope, it has a creamy-white color with a pinkish hue. ## Differentiation from Similar Minerals It can be confused with other platinum-group minerals (PGM), such as hongshiite, cuprorhodsite, or other natural alloys of noble metals. Definitive differentiation requires quantitative chemical analysis. ## Crystal Forms This mineral forms exclusively anhedral (irregular), rounded grains and aggregates of microscopic size.

Geological environment

## Genesis Michitoshiite-(Cu) forms in ultramafic igneous rock complexes. In its type locality (Onverwacht, RSA), it is a product of low-temperature hydrothermal processes that led to the redeposition and concentration of platinum-group elements within hortonolite-dunite-magnetite pegmatoid pipes, cutting archaic rocks of the Bushveld Complex. ## Mineral Associations This mineral co-occurs with other platinum-group minerals, such as cuprorhodsite, malanite, laurite, braggite, platarsite, as well as with bornite, chalcopyrite, digenite, magnetite, native gold, graphite, and serpentine-group minerals. ## Localities The only confirmed occurrence of this mineral worldwide is its type locality – the Onverwacht platinum mine in Limpopo Province, Republic of South Africa.

Rarity

Extremely rare

For collectors

## Quality Criteria Specimens of michitoshiite-(Cu) have purely scientific and reference value. Due to its microscopic nature, it does not form visually attractive specimens for the typical collector. The value of a specimen lies in the confirmed presence of the mineral in the rock matrix, documented by analyses.

Care and storage

## Cleaning Due to their microscopic size and occurrence as inclusions in other minerals, individual grains of michitoshiite-(Cu) are not subject to cleaning. Host rock specimens should be cleaned using methods appropriate for the dominant minerals, generally avoiding aggressive chemicals. ## What to Avoid Avoid contact with strong acids, which could damage both the mineral itself and the surrounding rock matrix. Abrupt temperature changes are also inadvisable. ## Storage Specimens containing michitoshiite-(Cu) should be stored under stable conditions, in sealed containers or display cases, to protect them from dust and mechanical damage. As a type material, it is preserved in the collections of scientific institutions.

External references

Sources

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