Luberoite

Chemical formula: Pt<sub>5</sub>Se<sub>4</sub>

An extremely rare platinum selenide with a metallic luster, found as microscopic grains in copper deposits.

## Characteristics Luberoite is an extremely rare mineral from the selenide group, chemically being platinum selenide. It occurs as small, anhedral (irregular) grains, whose size does not exceed 150 micrometers. These grains are usually dispersed within the mass of other minerals. Due to its microscopic size, its visual characteristics can only be assessed under a reflected light microscope, where it appears gray in reflected light. ## Physical Properties The mineral is characterized by a strong metallic luster and is completely opaque. Its density, calculated based on its chemical composition and unit cell parameters, is 12.36 g/cm³, which is a very high value, typical for platinum minerals. Hardness has not been precisely determined. ## Colors and Varieties Luberoite is an idiochromatic mineral with a constant, gray color. It does not form color varieties or commercial types. ## History and Name The mineral was described in 1981 by V. D. Sclar, B. K. Gheith, and R. S. Schwartz. Its name comes from the Lubero massif in the Kivu region (Democratic Republic of Congo), where its type locality, the Musonoi mine, is located. ## Uses Due to its extreme rarity and microscopic size, luberoite has no industrial application. It is solely an object of scientific interest and a valuable acquisition for specialized collectors of rare minerals (so-called "micromounts").

Properties

Luster
Metallic
Streak
Black
Density
12.36
Transparency
Opaque
Crystal system
Orthorhombic

Diagnostic features

## Identification Amateur identification of luberoite is impossible. Due to the microscopic size of the grains and their similarity to many other sulfides and selenides, its identification requires advanced analytical techniques, such as chemical composition analysis using an electron microprobe (EDS/WDS). Preliminary suspicion is possible based on optical analysis in reflected light under a microscope. ## Distinguishing from Similar Minerals Luberoite can be confused with other rare platinum group element selenides, with which it often coexists, such as oosterboschite (often forms intergrowths with it), verbeekite, or trogtalite. Definitive differentiation is only possible based on chemical analysis. ## Crystal Forms This mineral forms exclusively anhedral (irregular), shapeless grains. No well-formed crystals have been observed.

Geological environment

## Genesis Luberoite is a secondary mineral, forming in the supergene (cementation) zone of stratiform copper-cobalt deposits. Its presence is a result of weathering and alteration processes of primary ores. ## Mineral Associations This mineral occurs in association with other minerals of the cementation zone, such as digenite, bornite, covellite, as well as other rare selenides: oosterboschite, verbeekite, and trogtalite. ## Localities The only confirmed and significant occurrence of luberoite in the world is its type locality – the Musonoi mine, located near Kolwezi, in the Lualaba Province of the Democratic Republic of Congo.

Rarity

Extremely rare

For collectors

## Quality Criteria In the case of such a rare mineral occurring exclusively in microscopic form, the main criterion for value is certainty of identification, confirmed by chemical analysis. Additional advantages include the size and abundance of grains within the matrix and the presence of other rare associated minerals. ## Popular Localities The only source of collector specimens is the Musonoi mine in the Democratic Republic of Congo.

Care and storage

## Cleaning Luberoite specimens occur as microscopic grains embedded in a rock matrix and do not require cleaning. Any attempt at mechanical or chemical intervention can irrevocably destroy the specimen. ## What to Avoid Avoid contact with any chemicals, especially strong acids, which can dissolve it. Protect it from extreme temperatures and humidity. ## Storage Specimens containing luberoite should be stored in specialized micromount boxes, under stable room conditions, away from dust and chemicals.

Sources

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