Uduminelite

Chemical formula: Ca₃Al₈(PO₄)₂O₁₂·₂H₂O

Uduminelite is an extremely rare mineral, a hydrated aluminum and calcium phosphate, forming microscopic, colorless crystals in xenoliths.

## Characteristics Uduminelite is an exceptionally rare mineral from the phosphate group. It occurs as extremely small, lath-like or tabular crystals, typically not exceeding 0.2 mm in length and only a few micrometers in thickness. The crystals are colorless and transparent, with a vitreous luster. Due to their microscopic size, its visual characteristics can only be assessed under high magnification. ## Physical Properties Uduminelite crystals exhibit a vitreous luster. Hardness and density have not been precisely measured due to the small quantity and size of available material. The calculated density is 3.11 g/cm³. The mineral does not show fluorescence under ultraviolet light. ## Colors and Varieties Uduminelite is colorless. No colored or commercial varieties are known. ## History and Name The mineral's name comes from its discovery locality – the Udomi Plateau in Khabarovsk Krai, Russian Far East. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2021 (IMA2021-039). It was described by a team of mineralogists led by Igor V. Pekov. ## Uses Uduminelite has no practical or commercial applications. Its significance is purely scientific and as a collector's item, being an extremely rare and newly discovered mineral species.

Properties

Luster: Vitreous
Streak: White
Density: 3.11
Cleavage: Perfect on {100}
Fracture: Uneven
Transparency: Transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of uduminelite 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 its microscopic size and lack of characteristic macroscopic features. ## Distinguishing from Similar Minerals Based on appearance, it is indistinguishable from many other colorless, microscopic secondary minerals, such as wardite, crandallite, or other phosphates. Definitive differentiation requires specialized research equipment. ## Crystal Forms Uduminelite forms very small, elongated crystals with a lath-like or thin-tabular habit. They occur as single, isolated crystals or form small, loose aggregates on the surface of the host rock.

Geological environment

## Genesis Uduminelite forms under specific conditions within phosphorus- and aluminum-rich xenoliths that have been trapped and altered within volcanic rocks (ignimbrites). It is a secondary mineral, crystallizing in voids and fractures as a result of hydrothermal or pneumatolytic processes. ## Mineral Associations This mineral co-occurs with other rare phosphates and oxides. In the type locality, it was found in association with hematite, anorthoclase, quartz, anatase, bobierrite, wardite, stergiouite, sharyginite, and newly discovered minerals such as alumozppeite-2H and udryckaite. ## Localities The only confirmed occurrence of uduminelite in the world is its type locality – a xenolith found on the Udomi Plateau, near the Elgandzha volcano in Khabarovsk Krai, Russian Far East.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, the only criterion for evaluation is the quality and abundance of crystals visible under a microscope on a fragment of the host rock (matrix). Specimens with numerous, well-formed, and undamaged crystals, whose identity has been analytically confirmed, will be most highly valued. Association with other rare minerals is also important. ## Popular Localities The only source of specimens is the type locality in Russia. Material from this location is extremely difficult to acquire and is only available within specialized collecting circles and scientific institutions.

Care and storage

## Cleaning Due to its extreme rarity, microscopic size, and the fragility of crystals embedded in the rock matrix, mechanical cleaning is absolutely inadvisable. Specimens should be protected from dust and do not require cleaning. ## What to Avoid Avoid contact with any chemicals, ultrasound, and sudden temperature changes. The crystals are brittle and can be easily mechanically damaged. Protect them from vibrations and shocks. ## Storage Uduminelite specimens should be stored exclusively in specialized "micromount" boxes, which protect them from dust, moisture, and physical damage. Display is only possible under a microscope.

Sources

IMA Mineral List (CNMNC)