Scheuchzerite

Chemical formula: NaMn₂+₉Si₉V₅+O₂₈(OH)₄

Scheuchzerite is a very rare, brown sodium, manganese, and vanadium silicate, forming tiny, tabular crystals.

## Characteristics Scheuchzerite is an extremely rare mineral from the silicate group, chemically classified as a sodium, manganese, and vanadium silicate. It occurs as very small, tabular or bladed crystals, rarely exceeding 0.2 mm in length. These crystals often form rosette-like or radial aggregates. Its color ranges from brown to reddish-brown. ## Physical Properties The mineral is characterized by a vitreous luster and a brown streak. It is translucent. Due to the small size of the crystals, precise determination of hardness and density is difficult; the density calculated from the formula and cell parameters is approximately 3.45 g/cm³. ## History and Name Scheuchzerite was first described in 2011 by Joel Brugger, Nicolas Meisser, Karsten Braun, Sergey Krivovichev, and Robert Gault. The mineral is named in honor of Johann Jakob Scheuchzer (1672–1733), a Swiss physician and naturalist, a pioneer of paleontology and Alpine research. ## Uses Scheuchzerite has no industrial applications. Its significance is purely scientific and collectible due to its extreme rarity and status as a type locality mineral for its discovery site.

Properties

Luster: Vitreous
Streak: Brown
Density: 3.45
Cleavage: Perfect on {001}
Fracture: Uneven
Transparency: Translucent
Crystal system: Triclinic

Diagnostic features

## Identification In practice, scheuchzerite identification relies on its occurrence at the type locality. Characteristic features include very small, brown, tabular crystals forming radial aggregates on manganese rocks. Positive identification requires advanced analytical methods such as Raman spectroscopy or chemical analysis (EDS). ## Distinguishing from Similar Minerals It can be confused with other rare manganese silicates found in the same locality, such as braunite or wallisite. Visual differentiation is practically impossible and requires specialized research equipment. ## Crystal Forms It forms thin, tabular or bladed crystals, elongated along the [100] axis and flattened parallel to {001}. These crystals often combine into small, radial or rosette-like aggregates.

Geological environment

## Genesis Scheuchzerite forms as a result of metamorphic processes within manganese deposits. It occurs in fissures and small cavities in rocks rich in braunite and other manganese minerals. ## Mineral Associations This mineral is associated with braunite, aegirine, ganophyllite, quartz, rhodochrosite, tephroite, and wallisite. ## Localities The only confirmed locality for scheuchzerite worldwide (type locality) is the Fianel mine in the Ferrera Valley, Grisons canton, Switzerland.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" mineral, the value of a specimen is primarily determined by the quality and richness of the crystal aggregates on the rock matrix. The most desirable specimens are those with clearly formed, undamaged, radial crystal clusters, contrasting well with the surrounding minerals. Crystal size, although always microscopic, is also important. ## Popular Localities The only source of specimens is the Fianel mine in Switzerland, which makes every specimen from this locality extremely valuable for specialized collectors of rare minerals and micromounts.

Care and storage

## Cleaning Due to the extreme delicacy and small size of the crystals, mechanical cleaning is not recommended. If absolutely necessary, compressed air can be used from a safe distance to remove dust. Avoid contact with water and chemicals. ## What to Avoid Avoid all acids, solvents, and ultrasonics. Specimens are very brittle and sensitive to mechanical shock. Store away from moisture and sudden temperature changes. ## Storage Scheuchzerite specimens should be stored exclusively in specialized "micromount" boxes, protecting them from physical damage, dust, and moisture. Avoid exposure to direct sunlight.

Sources

IMA Mineral List (CNMNC)