Oosterboschite
Chemical formula: (Pd,Cu)₇Se₅
Oosterboschite is a very rare palladium and copper selenide, forming tiny, metallic grains, discovered in the Democratic Republic of Congo.
Properties
- Mohs hardness
- 4.5-5
- Density
- 0
- Transparency
- Opaque
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Identifying oosterboschite under collector conditions is practically impossible. It requires specialized analytical equipment, such as a reflected light microscope and an electron microprobe (EDS/WDS), to confirm its chemical composition (presence of palladium, copper, and selenium) and optical properties in reflected light. ## Distinguishing from Similar Minerals It can be confused with other rare selenides and platinum-group metal sulfides, such as chrisstanleyite, palladseite, or luberoite, with which it often co-occurs. Definitive differentiation is possible only through chemical analysis. ## Crystal Forms Oosterboschite forms exclusively anhedral (irregular) grains and aggregates, often intergrown with other minerals. No well-formed crystals have been observed.
Geological environment
## Genesis Oosterboschite forms in the oxidation zones of copper-cobalt deposits, where secondary concentration of selenium and platinum-group metals, particularly palladium, occurs. It is a product of hydrothermal or weathering processes under specific geochemical conditions. ## Mineral Associations This mineral co-occurs with other rare selenides. At the type locality, it was found in association with trogtalite, klockmannite, umangite, berzelianite, digenite, covellite, as well as palladseite and chrisstanleyite. ## Localities The only confirmed and described occurrence of oosterboschite in the world is the Musonoi mine, located near Kolwezi, in Lualaba Province, Democratic Republic of Congo.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of an oosterboschite specimen depends solely on the confirmation of its presence by a reputable laboratory and on the abundance and size of the grains in association with other rare minerals. Aesthetic value plays virtually no role here; scientific and documentary value is paramount. ## Popular Localities The only source of specimens is the historical type locality – the Musonoi mine in the DRC. Material from this location is extremely difficult to acquire and appears on the collector's market sporadically, usually originating from old research collections.
Care and storage
## Cleaning Due to the extreme rarity and small size of the grains, oosterboschite specimens embedded in the host rock should not be cleaned mechanically or chemically. Any attempts at cleaning may lead to damage or loss of material. ## What to Avoid Avoid contact with chemicals, acids, and ultrasonic cleaners. Temperature and humidity changes do not significantly affect the mineral embedded in the matrix, but the entire specimen should be protected from mechanical damage. ## Storage Oosterboschite specimens should be stored under stable conditions, preferably in a sealed "micromount" box, to protect them from dust and accidental damage. A label with precise location and identification is crucial.