Metaschoderite

Chemical formula: Al₂(PO₄)(V₅+O₄)·₆H₂O

Metaschoderite is a rare, hydrated aluminum phosphate-vanadate, occurring as earthy, yellow coatings in vanadium-rich deposits.

## Characteristics Metaschoderite is a secondary mineral, forming fine-grained, earthy aggregates and coatings. Its crystals are microscopic, lath-like, and visible only under high magnification. Macroscopically, specimens appear as powdery or compacted masses. ## Physical Properties It is characterized by an earthy luster and is translucent. Its density is approximately 2.45 g/cm³. Hardness has not been precisely determined, but due to its form and composition, it is a very soft mineral. ## Colors and Varieties It occurs in shades from pale yellow to yellow. No color varieties or commercial varieties are distinguished. ## History and Name The mineral's name refers to its relationship with schoderite — it is its monoclinic dimorph. It was first described in 1982. Its type locality is the Carlin Gold Mine in Eureka County, Nevada, USA. ## Applications Due to its rarity and unattractive form of occurrence, metaschoderite has no industrial applications. It is solely an object of interest for systematic collectors and scientists.

Properties

Mohs hardness: 1
Luster: Earthy
Streak: Pale yellow
Density: 2.45
Cleavage: Perfect on {010}
Fracture: Earthy
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification is primarily based on its occurrence and paragenesis. Characteristic features include pale yellow, earthy coatings in association with other rare phosphates and vanadates. Definitive identification requires advanced analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals Macroscopically, it is virtually indistinguishable from schoderite, with which it is dimorphous. It differs from schoderite in its crystallographic system (metaschoderite is monoclinic, while schoderite is triclinic). It can also be confused with other secondary vanadium minerals of similar color and form of occurrence. ## Crystal Forms It forms microscopic lath-like crystals that combine into fine-grained, earthy aggregates and coatings.

Geological environment

## Genesis It is a rare secondary mineral, formed in the oxidation zones of vanadium-rich deposits. At its type locality (Carlin mine), it occurs in altered chert and carbonate sediments. ## Mineral Associations It co-occurs with minerals such as schoderite, metavariscite, variscite, strengite, fluellite, crandallite, goyazite, and quartz. ## Localities The most important and type locality is the Carlin Gold Mine in Nevada, USA. It is also known from several other localities in Nevada, including the Gibellini mine.

Rarity

Very rare

For collectors

## Quality Criteria The collector's value of specimens depends almost exclusively on their origin (type locality) and the richness of their association with other rare minerals. Aesthetics are of secondary importance, as specimens are most often earthy coatings on the host rock. ## Popular Localities The most prized specimens come from the Carlin mine in Nevada, USA.

Care and storage

## Cleaning Specimens are extremely delicate. Cleaning should be limited to very careful dust removal using a soft brush or a stream of compressed air from a safe distance. Any contact with water should be avoided. ## What to Avoid Absolutely avoid water and other liquids, which can dissolve or damage the fragile aggregates. Protect from chemicals, ultrasound, high temperatures, and direct sunlight. The mineral is very soft and susceptible to abrasion. ## Storage Store in stable conditions, preferably in a closed, padded "micromount" box, to protect it from mechanical damage, dust, and moisture.

Sources

IMA Mineral List (CNMNC)