Anningite-(Ce)

Chemical formula: (Ca<sub>0.5</sub>Ce<sup>4+</sup><sub>0.5</sub>)(V<sup>5+</sup>O<sub>4</sub>)

Anningite-(Ce) is an extremely rare calcium and cerium vanadate, forming microscopic, orange-brown crystals.

## Characteristics Anningite-(Ce) is a mineral from the vanadate group, chemically classified as a calcium and cerium vanadate. It occurs as extremely small, tabular or bladed crystals, reaching sizes up to 100 micrometers in length and only a few micrometers in thickness. These crystals form radial or randomly oriented aggregates and clusters. Due to their microscopic size, its visual features are difficult to observe without specialized equipment. ## Physical Properties Anningite-(Ce) crystals exhibit an orange-brown color and a pale yellow streak. They have a vitreous luster and are transparent. Hardness and density have not been precisely measured due to the small size of the crystals; however, the density calculated based on the formula and unit cell parameters is 4.41 g/cm³. ## Colors and Varieties This mineral is known exclusively in one color variety – orange-brown. No other color or commercial varieties have been distinguished. ## History and Name Anningite-(Ce) was officially recognized as a new mineral by the International Mineralogical Association (IMA) in 2023 (IMA2023-076). Its name honors Mary Anning (1799–1847), an English paleontologist and fossil collector, for her contributions to the discovery of key Jurassic fossils in Great Britain. The "(Ce)" suffix in the name indicates the dominant rare earth element in its composition – cerium. ## Uses Anningite-(Ce) has no industrial application. Its significance is purely scientific and as a collector's item, as a unique and newly discovered mineral species.

Properties

Luster
Vitreous
Streak
Pale yellow
Density
4.41
Cleavage
Probably good, observed in one plane
Fracture
Uneven
Transparency
Transparent
Crystal system
Tetragonal

Diagnostic features

## Identification Identification of anningite-(Ce) is possible only through advanced analytical methods, such as Raman spectroscopy and chemical analysis using an electron microprobe (EDS/WDS). Visual identification in the field or even in a collection is impossible due to the microscopic size of the crystals and their similarity to other secondary minerals. ## Distinguishing from Similar Minerals This mineral can be confused with other microscopic vanadates or secondary minerals of similar coloration. Definitive distinction requires specialized chemical and crystallographic analysis. ## Crystal Forms Anningite-(Ce) forms very small, thin, tabular or bladed crystals that combine into radial aggregates or irregular clusters on the surface of the host rock.

Geological environment

## Genesis Anningite-(Ce) is a secondary mineral that forms in the oxidation zones of uranium-vanadium deposits. It forms in voids and on fracture surfaces in sandstones containing uraninite and other ore minerals. ## Mineral Associations This mineral co-occurs with other rare secondary minerals, such as carnotite, tyuyamunite, sherwoodite, as well as with quartz, which is the main component of the host rock (sandstone). ## Locations The only confirmed occurrence of anningite-(Ce) in the world (type locality) is the Burro Mine No. 7 uranium and vanadium mine in San Miguel County, Colorado, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, the collector's value of anningite-(Ce) depends on the richness and aesthetics of the crystal aggregates visible under the microscope. Most desirable are specimens with clearly formed, radial crystal clusters, contrasting with the rock matrix. The presence of associated minerals, especially other rare species, also increases the specimen's value. ## Popular Localities The only source of anningite-(Ce) specimens is its type locality – the Burro Mine in Colorado, USA. All specimens available on the collector's market originate from this single location.

Care and storage

## Cleaning Due to the extreme rarity and microscopic size of crystals embedded in a delicate matrix, mechanical cleaning is not recommended and can lead to the destruction of the specimen. Any contact with water, chemicals, or tools should be avoided. ## What to Avoid Specimens should be protected from vibrations, shocks, and contact with any liquids. They should not be exposed to ultrasound or chemical agents. Store away from sources of dust. ## Storage It is recommended to store specimens only in specialized, sealed "micromount" boxes, which protect them from mechanical damage and contamination. Display should only be done under a microscope.

Sources

Read more