Stankeithite

Chemical formula: Mn₂+Mn₂+Te₄+₄O₁₀

Stankeite is a very rare manganese tellurite, forming microscopic, dark red crystals with a strong luster.

## Characteristics Stankeite is a mineral from the oxide class, specifically a manganese tellurite. It occurs as very small, tabular or bladed crystals, rarely exceeding 0.2 mm in size. It typically forms radial or randomly oriented aggregates. Its crystals are characterized by an intense, dark red color and a strong, almost adamantine luster. ## Physical Properties Stankeite crystals are brittle. Due to the microscopic size of the crystals, many physical properties, such as hardness or density, have not been precisely measured, but only calculated based on crystallographic data. The calculated density is approximately 5.61 g/cm³. ## Colors and Varieties This mineral is monochromatic – it occurs exclusively in shades from dark red to reddish-brown. No varieties of it are distinguished. ## History and Name Stankeite was recognized as a new mineral species by the International Mineralogical Association (IMA) in 2021. Its name honors Frank Stanke (born 1960), a German mineral collector and amateur researcher specializing in tellurium mineralogy, who was the first to find the type material for this mineral. ## Applications Stankeite has no industrial applications. It is solely an object of scientific interest and a valuable acquisition for specialized collectors of rare minerals.

Properties

Luster: Adamantine
Streak: Red-brown
Density: 5.61
Cleavage: Perfect on {010}
Fracture: Brittle
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of stankeite is impossible without specialized equipment. Preliminary identification under a microscope is based on observing very small, tabular, dark red crystals with a strong luster, forming radial aggregates. Definitive identification requires advanced analytical methods, such as Raman spectroscopy or chemical analysis using an electron microprobe (EDS/WDS). ## Differentiation from Similar Minerals Stankeite can be confused with other rare, red tellurites occurring in paragenesis, such as ottoite, spiroffite, or magnussonite. Visual differentiation is practically impossible and requires crystallographic or chemical analysis. ## Crystal Forms Stankeite crystallizes as very small, thin, tabular or bladed crystals, often flattened. It forms small, radial or randomly arranged clusters and aggregates on the surface of the host rock.

Geological environment

## Genesis Stankeite is a hydrothermal mineral. It forms as a result of low-temperature processes occurring in ore veins rich in tellurium. It occurs in vugs and small fractures in volcanic rocks, such as andesites. ## Mineral Associations This mineral co-occurs with other, often equally rare, oxides and tellurites. Its most common associated minerals include: quartz, hematite, native tellurium, ottoite, spiroffite, magnussonite, as well as other unidentified Mn-Te-O phases. ## Localities The only confirmed occurrence of stankeite in the world is its type locality – the Otto Mountain mine, located approximately 13 km east of the town of Baker in San Bernardino County, California, USA. This is a historic gold and tellurium mine, known for the occurrence of many rare tellurium minerals.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a stankeite specimen is primarily assessed based on the richness and development of its microscopic crystals. The most prized specimens are those with numerous, well-formed, radial aggregates of intense red color, clearly visible against a light quartz matrix. The size of individual crystals, although always microscopic, also affects the value of the specimen. ## Popular Localities The only source of stankeite specimens is the Otto Mountain mine in California, USA. All specimens available on the collector's market originate from this single locality.

Care and storage

## Cleaning Stankeite specimens, due to their extreme rarity and microscopic size, should only be cleaned if absolutely necessary. Only compressed air (from a safe distance) should be used to remove dust. Any contact with water, and especially with chemicals, is highly inadvisable. ## What to Avoid Avoid contact with all liquids and chemical agents. The crystals are very small and brittle, so they must be protected from shocks, impacts, and abrasion. The specimen should not be exposed to ultrasound or sudden temperature changes. ## Storage Stankeite specimens are best stored in their original, sealed "micromount" box, protecting them from dust and mechanical damage. Display should only take place under a microscope to avoid accidental damage or loss of the microscopic crystals.

Sources

IMA Mineral List (CNMNC)