Cattiite

Chemical formula: Mg₃(PO₄)₂·₂₂H₂O

Cattiite is a rare, hydrated magnesium phosphate, forming colorless, tabular crystals with low hardness.

## Characteristics Cattiite is a hydrated magnesium phosphate that occurs extremely rarely in nature. It typically forms small, colorless, tabular crystals, often gathered into rosette-like or radial aggregates. Due to its delicacy and chemical composition, it is an unstable mineral in dry air, where it easily loses water and transforms into newberyite. ## Physical Properties This mineral is characterized by very low hardness, measuring 2 on the Mohs scale, which makes it susceptible to scratching. Its density is also low, at 1.65 g/cm³. The crystals exhibit a vitreous luster and are transparent. It possesses excellent cleavage in one direction. ## Colors and Varieties Cattiite is a colorless mineral. No colored varieties have been identified. ## History and Name The mineral's name honors Professor M. Catti from the University of Milan (Italy) for her contributions to mineral crystal chemistry. It was officially described and approved as a new mineral species in 2000, and its discovery was made in the Kovdor Zheleznyi mine in Russia. ## Uses Cattiite has no industrial applications. Its significance is purely scientific and collectible, although due to its rarity and instability, it is primarily sought after by specialized collectors.

Properties

Mohs hardness: 2
Luster: Vitreous
Streak: White
Density: 1.65
Cleavage: (001)
Fracture: Irregular/Uneven
Transparency: Transparent
Crystal system: Triclinic

Diagnostic features

## Identification Cattiite can be identified by its characteristic, colorless, and transparent tabular crystals, often forming rosette-like aggregates. A key diagnostic feature is its extremely low hardness (2 on the Mohs scale) and instability in dry air – if left exposed, it quickly becomes opaque and disintegrates. ## Distinguishing from Similar Minerals It can be confused with other colorless, secondary phosphate or sulfate minerals, such as gypsum or brushite. It differs from gypsum by its different crystal habit and genesis. From brushite, which is also unstable, it can be difficult to distinguish without advanced studies (e.g., XRD). However, the reaction to dry air is very characteristic of cattiite. ## Crystal Forms Cattiite crystals are tabular, flattened parallel to the plane of perfect cleavage. They usually occur as small, radial or rosette-like aggregates, as well as thin coatings and efflorescences.

Geological environment

## Genesis Cattiite is a secondary mineral, formed under very specific conditions. It forms in the weathering zones of deposits rich in magnesium and phosphorus. Its typical genesis is associated with low-temperature hydrothermal processes acting on carbonate-apatite or dolomite rocks. ## Mineral Associations This mineral co-occurs with other phosphates and carbonates. In its type locality, it was found in association with bobierrite, dolomite, pyrite, manasseite, pyrochroite, and kovdorskite. ## Localities The most important and also the type locality for cattiite is the Kovdor Zheleznyi mine on the Kola Peninsula in Russia. This is the only locality from which well-formed, collectible specimens of this mineral originate.

Rarity

Very rare

For collectors

## Quality Criteria The most prized cattiite specimens are those with well-formed, sharp, and transparent crystals forming aesthetic, rosette-like aggregates. The size of the crystals and their pristine condition – without signs of dehydration (opacity) – are important. A contrasting matrix, though rare, can increase the specimen's value. ## Popular Localities The only source of cattiite specimens of collector significance is the Kovdor massif in the Murmansk Oblast, Russia.

Care and storage

## Cleaning Cattiite specimens are extremely delicate and sensitive to environmental changes. Mechanical cleaning is not recommended. If absolutely necessary, a stream of compressed air can be used from a distance to remove loose dust particles. Contact with water and all chemicals should be avoided. ## What to Avoid This mineral is unstable under low humidity conditions. In dry air, it rapidly dehydrates, losing its structure and transforming into newberyite, which manifests as a loss of transparency and crystal disintegration. Temperature changes, direct sunlight, and all chemicals, including acids and detergents, must be strictly avoided. ## Storage Cattiite requires storage under special conditions. It is best kept in a tightly sealed container (e.g., a "membrane box") with a small amount of added water (e.g., a damp cotton swab, but not in direct contact with the specimen) to ensure high relative humidity. Protect from shocks and vibrations.