Namibite

Chemical formula: Cu<sup>2+</sup>(Bi<sup>3+</sup>O)<sub>2</sub>V<sup>5+</sup>O<sub>4</sub>(OH)

Namibite is a rare copper bismuth oxyvanadate mineral, forming characteristic, dark green, tabular crystals.

## Characteristics Namibite is a rare mineral from the vanadate group, chemically classified as a copper bismuth hydroxyl oxyvanadate. It occurs as very small, tabular or bladed crystals, which rarely exceed 1 mm in length. These crystals often form rosette-like or radial aggregates, as well as thin coatings and earthy masses. Its color is characteristic - from dark green to almost black. ## Physical Properties Namibite crystals exhibit a hardness of approximately 4.5-5 on the Mohs scale. They have a luster ranging from vitreous to slightly resinous. It is an opaque mineral. Due to the small size of the crystals, its density is difficult to measure, but the calculated value is approximately 7.76 g/cm³. ## Colors and Varieties This mineral occurs in uniform shades of dark green, often so saturated that it appears black. No color or commercial varieties are distinguished. ## History and Name Namibite was discovered and described in 1981 by Oleg von Knorring and Th. G. Sahama. Its name comes from its discovery locality - the Namib Desert in Namibia, where the first specimens were found. ## Uses Due to its rarity and microscopic crystal size, namibite has no industrial application. It is solely an object of interest for collectors specializing in rare minerals and for scientists.

Properties

Mohs hardness
4.5-5
Luster
Vitreous to resinous
Streak
Light green
Density
7.76
Cleavage
Good on {001}
Fracture
Uneven
Transparency
Opaque
Crystal system
Monoclinic

Diagnostic features

## Identification Namibite is identified by its characteristic dark green color, tabular crystal form, and specific occurrence in the oxidation zones of polymetallic deposits. It forms small aggregates, often in association with other secondary bismuth and copper minerals. Final identification requires advanced methods such as X-ray diffraction (XRD) or chemical analysis (EDS). ## Distinguishing from Similar Minerals It can be confused with other green, secondary copper minerals such as malachite, brochantite, or atacamite. However, it is distinguished by its much darker shade of green, specific tabular crystal form, and co-occurrence with bismuth minerals. Unlike malachite, namibite does not react with hydrochloric acid. ## Crystal Forms Crystals are typically very small, tabular or bladed in habit, flattened parallel to {001}. They often form fan-like, rosette-like, or radial aggregates. It also occurs as earthy masses and crusts.

Geological environment

## Genesis Namibite is a secondary mineral, forming in the oxidation zones (so-called gossans) of hydrothermal polymetallic deposits that are rich in copper, bismuth, and vanadium. It forms as a result of the weathering of primary ores containing these elements. ## Mineral Associations It most commonly co-occurs with other secondary minerals such as bismutite, beyerite, malachite, brochantite, mottramite, duftite, cerussite, wulfenite, as well as with quartz and iron oxides (goethite, hematite). ## Localities The most important and classic localities for this mineral are in Namibia, particularly in the Ugab River area and on Mesopotamia Farm 504. It is also known from several other places in the world, including the Clara mine in the Black Forest (Germany), the Silberbrünnle mine in the Zastler Valley (Germany), and the Broken Hill area in New South Wales (Australia).

Rarity

Very rare

For collectors

## Quality Criteria Specimens with well-formed, sharp crystals forming aesthetic, rosette-like or radial aggregates are most valued by collectors. A contrasting, light matrix rock (e.g., quartz) enhances visual appeal. Crystal size is a key factor - specimens with crystals exceeding 1 mm are considered exceptional. Association with other rare minerals is also important. ## Popular Localities Specimens from the type locality in Namibia are the most classic. Well-crystallized namibites from the Clara mine in Germany, which often form attractive compositions with other rare secondary minerals, are also highly prized.

Care and storage

## Cleaning Namibite specimens should be cleaned very carefully, preferably using compressed air to remove dust. Any mechanical cleaning (e.g., with a brush) or use of water is discouraged due to the fragility and small size of the crystals, which can easily be damaged or detached from the matrix rock. ## What to Avoid Contact with all chemicals, including acids and strong bases, which can destroy the mineral, should be avoided. It should not be heated or subjected to ultrasound. Prolonged exposure to intense light is not recommended, although there is no evidence of it fading. ## Storage Specimens with namibite are best stored in closed, stable containers (e.g., "micromount" type) to protect them from dust, moisture, and mechanical damage. Storage in areas with high humidity should be avoided.

Sources

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