Oosterboschite: Properties and Occurrences

Oosterboschite is a rare selenide mineral with the formula (Pd,Cu)7Se5. It is an orthorhombic black mineral containing copper, palladium, and selenium. It occurs as composite grains of anhedral crystals ranging from a few µm to several hundred µm in size. It crystallizes in the orthorhombic crystal system. It has a creamy yellow color and a Moh’s hardness of 5. It is not radioactive.

It was amed after Robert Oosterbosch, mining geologist. He was involved with the development and exploitation of ore bodies in Katanga.

General Information

  • Category: Selenide minerals
  • Formula: (repeating unit) (Pd,Cu)7Se5
  • Crystal system: Orthorhombic
  • Color: Creamy yellow-white

Properties

It crystallizes in the orthorhombic crystal system. It has a creamy yellow color and a Moh’s hardness of 5. It is often found as grains with no clear shape. The crystals are opaque and often no bigger than 0.4 mm.

  • Crystal habit: Anhedral grains
  • Mohs scale hardness: 5
  • Luster: Metallic
  • Streak: Black
  • Diaphaneity: Opaque
  • Density: 8.48 (calculated)
  • Ultraviolet fluorescence: None
  • Solubility: Insoluble

Occurrence: In the zone of oxidation (Musonoi mine, Congo).

The mineral was approved by the IMA in 1970, after being discovered in the Musonoi Cu–Co mine, near Kolwezi, Katanga Province, Congo. It was later also discovered at the Copper Hills prospect, East Pilbara, Australia, and at Hope’s Nose, Torquay, Devon, England. It is a new mineral from gold-bearing carbonate veins in Middle Devonian limestones at Hope’s Nose, Torquay, Devon, England. It is often found in the oxidation zones of the mines, together with verbeekite, trogtalite, selenian digenite, covellite, gold, and chrisstanleyite. It was named after Robert Oosterbosch, a Belgian mining engineer that was very active in the Katanga region, where the type locality is also located.

Association: Verbeekite, trogtalite, selenian digenite, covellite (Musonoi mine, Congo); gold, chrisstanleyite, verbeekite (Hope’s Nose, England).

It is associated with palladian and argentian gold, fischesserite, clausthalite, eucairite, tiemannite, umangite, a Pd arsenide-antimonide (possibly mertieite II), cerussite, calcite and bromian chlorargyrite.