Nabiasite

Chemical formula: BaMn₂+₉(V₅+O₄)₆(OH)₂

Nabiasite is a very rare barium manganese vanadate, forming small, tabular crystals of a characteristic reddish-brown color.

## Characteristics Nabiasite is a hydrated barium manganese vanadate, occurring extremely rarely. It forms very small, tabular or bladed crystals, which usually do not exceed 0.3 mm in length. These crystals often form rosette-like or radial aggregates. Due to its small size, it is a mineral primarily available to specialized collectors and scientific institutions. ## Physical Properties Nabiasite crystals exhibit a vitreous luster. They are brittle and have perfect cleavage in one direction. The mineral's density is approximately 4.85 g/cm³. ## Colors and Varieties Nabiasite has a characteristic reddish-brown to brownish-black color. In transmitted light, it reveals pleochroism in shades from reddish-brown to yellowish-brown. No varieties have been distinguished. ## History and Name The mineral was discovered in the Tachgagalt manganese mine in the Souss-Massa region of Morocco. Its description was approved by the International Mineralogical Association (IMA) in 1998. The name "nabiasite" comes from the combination of the symbols of the elements comprising it: sodium (Na), barium (Ba), and sulfur (S), which was a result of an erroneous preliminary chemical analysis. Although later, more accurate studies showed a different composition (with dominant manganese and vanadium, and without sodium and sulfur), the original name was retained.

Properties

Mohs hardness: 3-4
Luster: Vitreous
Streak: Red-brown
Density: 4.85
Cleavage: Perfect on {001}
Fracture: Uneven
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Amateur identification of nabiasite is practically impossible due to its microscopic size and occurrence. Identification requires advanced analytical techniques, such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS). Visual characteristics may include its reddish-brown color and the form of small, tabular crystals in radial aggregates. ## Distinction from Similar Minerals Nabiasite can be confused with other rare, fine-grained manganese and vanadium minerals from the same locality, such as gamagarite or hedyphane. Definitive distinction is possible only through chemical and crystallographic analysis. ## Crystal Forms Nabiasite forms thin, tabular crystals with a hexagonal outline, elongated in one direction. These crystals combine into radial or rosette-like aggregates, as well as fan-like clusters.

Geological environment

## Genesis Nabiasite forms as a result of hydrothermal processes in manganese ore deposits. It occurs in small fissures and rock vugs. In its type locality (Tachgagalt), it is associated with a late stage of vanadate mineralization cutting through braunite- and hausmannite-rich rocks. ## Mineral Associations This mineral co-occurs with other rare minerals, such as gamagarite, hedyphane, braunite, hausmannite, andradite, barite, and quartz. ## Localities The only confirmed and described occurrence of nabiasite in the world is its type locality - the Tachgagalt manganese mine, located near Ouarzazate in the Souss-Massa region of Morocco.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a nabiasite specimen is determined by the richness and development of its microscopic crystals. The most valued specimens are those with clearly formed, radial aggregates of an intense, reddish-brown color, contrasting well with the rock matrix. Due to the microscopic nature of the mineral, the quality of the photomicrography documenting the specimen is crucial. ## Popular Localities The only source of nabiasite specimens is the Tachgagalt mine in Morocco, making it extremely important for collectors specializing in rare minerals or minerals from this specific locality.

Care and storage

## Cleaning Due to the extreme rarity, small size, and brittleness of the crystals, mechanical cleaning is highly inadvisable. Specimens should be left undisturbed. If cleaning is absolutely necessary, compressed air (from a safe distance) can be used to remove dust. ## What to Avoid Avoid contact with all chemicals, acids, and detergents. Do not use ultrasonic cleaners. The mineral is brittle, so it must be protected from impacts and vibrations. ## Storage Nabiasite specimens, typically microscopic, should be stored in specialized "micromount" boxes, which protect them from mechanical damage and dust. Avoid exposure to extreme temperatures and humidity.

Sources

IMA Mineral List (CNMNC)