Gottlobite

Chemical formula: CaMg(V⁵⁺O₄)(OH)

Gottlobite is a rare calcium and magnesium vanadate, distinguished by its intense orange color and adamantine luster.

## Characteristics Gottlobite is a mineral from the vanadate group, belonging to the adelite-descloizite group. It forms very small, tabular or prismatic crystals, rarely exceeding 1 mm, which often occur as radial aggregates or rosettes. Its most characteristic feature is its intense, vivid color, ranging from orange to orange-brown, combined with a strong, almost adamantine luster. ## Physical Properties This mineral is characterized by a hardness of 4.5 on the Mohs scale. It is transparent, and its luster is described as adamantine. The fracture is uneven, sometimes conchoidal. The streak left on a plate is brownish-white. ## Colors and Varieties Gottlobite occurs in uniform, characteristic shades from orange to orange-brown. No color or commercial varieties are distinguished. ## History and Name The mineral's name comes from its discovery locality – Gottlob Hill in Thuringia, Germany. It was first described in 1999 by Werner Krause, Heinz-Jürgen Bernhardt, Herbert Effenberger, and Christian Lenz. The type locality is the Glücksstern mine. ## Applications Due to its extreme rarity and small crystal size, gottlobite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals and for scientific institutions.

Properties

Mohs hardness: 4.5
Luster: Adamantine
Streak: Brownish white
Density: 0
Fracture: Irregular/Uneven,Conchoidal
Transparency: Transparent
Crystal system: Orthorhombic

Diagnostic features

## Identification Field identification of gottlobite is practically impossible due to the size of its crystals. In a collection, it is recognized by its characteristic orange color, adamantine luster, specific form of small, tabular crystals forming aggregates, and its association with other minerals from the type locality. Final confirmation requires advanced analytical methods (XRD, EDS). ## Distinguishing from Similar Minerals It can be confused with other rare vanadates of similar color, such as descloizite or mottramite, which often occur in similar environments. Differentiation requires chemical and crystallographic analysis. From more common minerals like vanadinite, it differs in crystal form and chemical composition (presence of magnesium). ## Crystal Forms It forms very small, thin, tabular crystals with a rectangular or square cross-section. These crystals often combine into radial, rosette-like, or fan-shaped aggregates.

Geological environment

## Genesis It is a secondary mineral, forming in the oxidation zones of ore deposits containing vanadium. It forms in voids and fissures of sedimentary rocks, such as sandstones and conglomerates, which have undergone hydrothermal processes. ## Mineral Associations At the type locality (Glücksstern mine), it co-occurs with minerals such as quartz, barite, goethite, hematite, and other rare vanadates like tangeite, mounanaite, and fianelite. ## Localities It is an extremely rare mineral, known mainly from its type locality in Germany – the Glücksstern mine on Gottlob Hill in Friedrichroda, Thuringian Forest. Its occurrence has also been confirmed in several other places worldwide, including the Carl-Friedrich mine in Baden-Württemberg (Germany) and the Praborna mine in Italy.

Rarity

Very rare

For collectors

## Quality Criteria For collectors, the size and quality of crystal development are most important, although these are always very small. Specimens with distinct, undamaged, radial aggregates of intense orange color are highly valued. Contrast with a light matrix rock (e.g., quartz) also enhances the visual appeal of the specimen. The abundance of crystals on the sample surface is a key factor. ## Popular Localities The only source of specimens of collector significance is the type locality – the Glücksstern mine in Thuringia, Germany. Specimens from this location are most sought after by collectors specializing in "microminerals" and rare minerals.

Care and storage

## Cleaning Due to the small size and fragility of the crystals, mechanical cleaning is not recommended. If absolutely necessary, compressed air can be used to remove dust. Contact with water and any chemicals should be avoided. ## What to Avoid Avoid ultrasonics, steam cleaners, acids, solvents, and sudden temperature changes. The mineral is brittle and susceptible to mechanical damage. ## Storage Gottlobite specimens, usually as microcrystals on matrix, should be stored in stable conditions, in a sealed "micromount" box, to protect them from dust, moisture, and physical damage. They are best displayed under a microscope.