Owensite

Chemical formula: (Ba,Pb₂+)₆(Cu₁+,Fe₂+,Ni₂+)₂₅S₂-₂₇

Owensite is a very rare barium, lead, and copper sulfide, forming tiny, metallic inclusions in other minerals.

## Characteristics Owensite is an extremely rare sulfide mineral, described only in 1995. It occurs as very fine, anhedral (irregularly shaped) grains, usually not exceeding 200 micrometers in size. These grains are most often intergrown within crystals of another rare mineral, zofallite. Due to its microscopic size and opacity, its visual characteristics can only be assessed under a reflected light microscope, where it presents a metallic appearance. ## Physical Properties As an opaque mineral, owensite is characterized by a metallic luster. Its hardness and density have not been precisely measured due to the small size of the samples and their inclusionary nature. The density calculated based on its chemical formula and unit cell parameters is 5.55 g/cm³. ## Colors and Varieties Under a reflected light microscope, owensite appears gray with a slight reddish tint. It does not exhibit pleochroism or internal reflections. No varieties of owensite are known. ## History and Name The mineral was discovered in the Broken Hill mine in New South Wales, Australia. It was officially recognized by the International Mineralogical Association (IMA) in 1994 and described in 1995. Its name honors Dr. David R. Owens (born 1941), a Canadian mineralogist working at CANMET (Canada Centre for Mineral and Energy Technology), in recognition of his contributions to ore mineralogy, especially using ore microscopy.

Properties

Luster: Metallic
Density: 5.55
Cleavage: None
Transparency: Opaque
Crystal system: Hexagonal

Diagnostic features

## Identification Identification of owensite is possible only through advanced laboratory techniques. It requires analysis under a reflected light (ore) microscope and confirmation of its chemical composition by X-ray microanalysis (EDS/WDS). Its characteristic feature is its co-occurrence with zofallite and other rare sulfides in the Broken Hill deposit. ## Distinguishing from Similar Minerals Under the microscope, it can be confused with other gray, metallic sulfides. Definitive differentiation from similar minerals, such as tetrahedrite or other sulfosalts, requires chemical analysis to confirm the unique combination of barium, lead, and copper. ## Crystal Forms Owensite occurs exclusively in the form of anhedral, i.e., irregularly shaped, rounded grains. No well-formed crystals have been observed.

Geological environment

## Genesis Owensite formed as a result of high-grade metamorphic processes (amphibolite to granulite facies metamorphism) affecting sulfide deposits. It is a product of recrystallization and reactions between minerals under extreme pressure and temperature conditions. ## Mineral Associations This mineral occurs in paragenesis with other, often rare, minerals. It is most commonly found as inclusions in zofallite. It is also associated with galena, sphalerite, chalcopyrite, pyrrhotite, alabandite, tetrahedrite, and other rare minerals such as watanabeite or menchettiite. ## Localities The only confirmed locality of owensite in the world is its type locality - the Broken Hill deposit in New South Wales, Australia.

Rarity

Extremely rare

For collectors

## Quality Criteria Owensite does not form macroscopic specimens, so traditional evaluation criteria such as size, crystal form, or luster do not apply. The collectible value of a sample lies solely in its scientific and documentary value. The most valuable specimens are those in which the presence of owensite has been analytically confirmed, and the mineral itself is clearly visible on a polished surface under a microscope, in association with other rare species.

Care and storage

## Cleaning Due to the extreme rarity and microscopic size of specimens, which occur as inclusions in other minerals, owensite is practically never subjected to cleaning. Any attempts at mechanical or chemical intervention would destroy the sample. ## What to Avoid All chemicals, ultrasonics, and rapid temperature changes should be avoided. As a sulfide, it may be sensitive to acids and oxidation in a humid environment. ## Storage Specimens containing owensite should be stored under stable, dry conditions, away from chemical contaminants. The safest place is a padded "micromount" box or a specialized mineralogical display case.

External references

https://en.wikipedia.org/wiki/https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FOwensite