Paravauxite

Chemical formula: Fe²⁺Al₂(PO₄)₂(OH)₂·₈H₂O

Paravauxite is a rare, hydrated iron and aluminum phosphate, forming characteristic, colorless or greenish, tabular crystals.

## Characteristics Paravauxite is a rare mineral from the phosphate group, chemically classified as a hydrated iron and aluminum phosphate. It occurs as well-formed, tabular or prismatic crystals, often gathered in radial or fan-shaped aggregates. Crystals are usually small, rarely exceeding a few millimeters in length. A characteristic feature is their vitreous luster and transparency. ## Physical Properties This mineral is relatively soft, with a hardness of 3 on the Mohs scale. It has a vitreous luster, and on cleavage surfaces, it can be pearly. It is transparent to translucent. The density of paravauxite is approximately 2.39 g/cm³. ## Colors and Varieties Paravauxite is most often colorless or has delicate shades of green, white, or yellow. Its color is usually pale and subtle. No named color varieties or commercial varieties are distinguished. ## History and Name The mineral was first described in 1922 by Samuel Gordon based on specimens found in the Llallagua mine in Bolivia. The name "paravauxite" refers to its chemical and structural similarity to vauxite, with the Greek prefix "para" meaning "near" or "beside." ## Uses Paravauxite has no industrial applications. Its significance is purely scientific and collectible; it is valued by collectors of rare minerals, especially for well-formed crystals from its type locality in Bolivia.

Properties

Mohs hardness: 3
Color: Pale greenish white to colorless; colorless in transmitted light. also gray-white or Light brown.
Luster: Vitreous
Streak: White
Density: 2.36
Cleavage: on {010}, perfect.
Fracture: Conchoidal
Transparency: Transparent,Translucent
Crystal system: Triclinic

Diagnostic features

## Identification Paravauxite can be identified by its characteristic, tabular crystals, often forming radial aggregates. Key features include vitreous luster, low hardness, and occurrence in paragenesis with other rare phosphates in hydrothermal veins. ## Distinguishing from Similar Minerals Paravauxite is very similar to vauxite and metavauxite, with which it often co-occurs. Distinguishing these minerals without advanced analytical methods (such as X-ray diffraction) is practically impossible. It differs from quartz by its significantly lower hardness. From other visually similar phosphates, such as wavellite, it differs in crystal form – wavellite forms spherical aggregates, while paravauxite forms flattened, tabular crystals. ## Crystal Forms Paravauxite crystals are tabular, flattened along one of the crystallographic axes, or short prismatic. They often occur as fan-shaped, radial, or nearly spherical aggregates, as well as rosettes on the surface of the host rock.

Geological environment

## Genesis Paravauxite is a secondary mineral, formed in the oxidation zones of ore deposits as a result of hydrothermal processes. It forms in veins cutting sedimentary rocks, such as sandstones, or in phosphatic pegmatites. ## Mineral Associations This mineral most often co-occurs with other phosphates, especially vauxite, metavauxite, and wavellite. It is also frequently accompanied by quartz, pyrite, cassiterite, and other ore minerals. ## Localities The most important and globally renowned locality for paravauxite, from which the best specimens originate, is the Siglo XX mine in Llallagua, Potosí Department, Bolivia. This is the type locality for this mineral. Occurrences have also been reported in the Willard mine in Pershing County, Nevada (USA).

Rarity

Rare

For collectors

## Quality Criteria The most prized paravauxite specimens are characterized by sharp, well-formed, and transparent crystals, forming aesthetic, radial aggregates. The absence of damage and attractive placement on a small rock matrix are important. Specimens with a distinct, even if pale, greenish color are generally more desirable than colorless ones. Crystal size also matters, although even small but perfectly formed groups are highly valued. ## Popular Localities Specimens from the historical locality of Llallagua in Bolivia are by far the most sought after by collectors. Minerals from this location are considered the global standard for paravauxite.

Care and storage

## Cleaning Paravauxite specimens should be cleaned very carefully, using a soft brush to remove dust. If wet cleaning is necessary, it is recommended to use only distilled water and to dry very gently with compressed air or allow to air dry naturally. Ultrasonic cleaners should be avoided. ## What to Avoid Paravauxite is a mineral sensitive to chemicals, especially acids, which can damage it. It is also relatively soft and brittle, susceptible to scratches and mechanical damage. Avoid sudden temperature changes and prolonged exposure to strong sunlight, although it is not known to fade. ## Storage Collectible paravauxite specimens are best stored in separate, padded boxes to avoid contact with harder minerals. They should be protected from dust and moisture. Due to its brittleness, it is not suitable for mounting in jewelry or for frequent handling.