Jörgkellerite

Chemical formula: (Na,&#9744;)<sub>3</sub>Mn<sup>3+</sup><sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>(CO<sub>3</sub>)(O,OH)<sub>2</sub>·5H<sub>2</sub>O

Jörgkellerite is a rare phosphate mineral characterized by its intense violet color, found as small, tabular crystals.

## Characteristics Jörgkellerite is a complex hydrated sodium manganese phosphate with a carbonate group. It forms very small, thin, tabular crystals, rarely exceeding 1 mm in length. These crystals often occur in radial or randomly oriented aggregates, forming coatings and crusts on the surface of the host rock. Its most distinctive feature is its intense violet to purplish-red color. ## Physical Properties This mineral is characterized by a vitreous luster and is transparent to translucent. It has a relatively low hardness, approximately 2.5 on the Mohs scale, making it a brittle mineral. The calculated density is about 2.65 g/cm³. Crystals exhibit perfect cleavage in one direction. ## Colors and Varieties Jörgkellerite occurs in a characteristic range of colors from violet to purplish-red. No varieties have been described. ## History and Name The mineral was discovered in an LCT (lithium, cesium, tantalum) type pegmatite at Clementine II, in the Erongo Mountains, Namibia. It was described and approved as a new mineral species by the International Mineralogical Association (IMA) in 2013 (IMA2013-078). The name honors Dr. Jörg Keller (born 1938), a German volcanologist and petrologist from the University of Freiburg, for his contributions to the mineralogy and petrology of volcanic rocks. ## Applications Due to its extreme rarity and microscopic crystal size, jörgkellerite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals and a subject of scientific research.

Properties

Mohs hardness
2.5
Luster
Vitreous
Streak
Light purple
Density
2.65
Cleavage
Perfect on {0001}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Trigonal

Diagnostic features

## Identification Jörgkellerite is primarily recognizable by its unique, intense violet color, thin tabular crystal habit, and specific occurrence. Vitreous luster and low hardness are auxiliary features. Final identification requires advanced analytical methods, such as Raman spectroscopy or chemical analysis (EDS). ## Distinguishing from Similar Minerals It can be distinguished from Purpurite by its crystal habit (Purpurite is usually massive) and environment of occurrence. Other violet phosphates, such as Strengite, usually have a different crystal habit (often spherulitic or radial) and different associated minerals. ## Crystal Forms Crystals are very thin, tabular, with a hexagonal outline. They typically form small, rosette-like or radial aggregates, as well as irregular clusters and crusts on the host rock.

Geological environment

## Genesis Jörgkellerite is a secondary mineral that crystallizes in the late stage of hydrothermal processes in complex granitic pegmatites, rich in lithium and phosphorus. It forms in rock cavities and fissures as a result of the alteration of earlier phosphate minerals. ## Mineral Associations This mineral occurs in association with other rare phosphates. At the type locality (Clementine II, Namibia), it was found in association with Eosphorite, Cyrilovite, Wardite, Rockbridgeite, Strengite, Stewartite, Childrenite, Apatite, Quartz, Albite, and Muscovite. ## Localities The only confirmed and described occurrence of jörgkellerite in the world is its type locality: Clementine II pegmatite, Uis Farm, Erongo Mountains, Erongo Region, Namibia.

Rarity

Very rare

For collectors

## Quality Criteria The most highly valued specimens are those with rich coverage of intensely colored, violet crystals on a contrasting matrix. The size of individual crystals (though always small) and the aesthetics of the entire aggregate are also important. Specimens with well-defined, undamaged crystals in rosette-like aggregates are particularly sought after. ## Popular Localities The only source of jörgkellerite specimens is its type locality in the Erongo Mountains, Namibia. All specimens available on the collector's market originate from this single location.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Due to its low hardness and brittleness, mechanical contact, including brushes, should be avoided. Contact with water is inadvisable due to the risk of damage to delicate crystals and potential reaction with associated minerals. ## What to Avoid All chemicals, especially acids, which can destroy the mineral, must be absolutely avoided. Specimens are susceptible to mechanical damage, so they should be protected from impacts and scratches. They should also not be heated or exposed to prolonged strong light. ## Storage Store in stable conditions, in a sealed "micromount" box, to protect against dust, moisture, and physical damage. It is best to keep it away from other minerals to avoid abrasion.

Sources

Read more