Marićite

Chemical formula: NaFe<sup>₂+</sup>PO<sub>₄</sub>

A rare sodium iron phosphate, found mainly in siderite concretions and meteorites, forming characteristic radial aggregates.

## Characteristics Maricite is a rare mineral from the phosphate group, chemically classified as a sodium iron phosphate. It typically occurs as granular masses or characteristic radial aggregates, which can reach several centimeters in diameter. Well-formed, tabular crystals are rare and usually very small. It is a brittle mineral. ## Physical Properties Maricite has a hardness of 4-4.5 on the Mohs scale. Its luster is described as vitreous to greasy on fresh surfaces. It is translucent to opaque. Its density is approximately 3.66 g/cm³. ## Colors and Varieties This mineral is most often colorless, pale gray, pale yellow, or light brown. After prolonged exposure to air, its surface may darken and dull. No distinct color varieties or commercial varieties are recognized. ## History and Name Maricite was discovered in 1976 in siderite concretions in river sediments of the Big Fish River in Yukon, Canada. Its name honors Professor Luka Marić (1899-1979), long-time head of the Department of Mineralogy and Petrology at the University of Zagreb, in recognition of his contributions to mineralogy and petrology. ## Uses Due to its rarity and small size, maricite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals and scientists studying phosphate processes in various geological environments, including meteorites.

Properties

Mohs hardness: 4-4.5
Luster: Vitreous to greasy
Streak: White
Density: 3.66
Cleavage: None
Fracture: Uneven to conchoidal
Transparency: Translucent to opaque
Crystal system: Orthorhombic

Diagnostic features

## Identification A characteristic feature of maricite is its radial aggregates within siderite concretions or as inclusions in other minerals. Its occurrence in a specific geological environment (concretions, meteorites) is a key indicator. Identification is usually confirmed by analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals Maricite can be confused with other phosphates occurring in similar parageneses, such as vivianite (which, however, often has a blue or green color and is softer) or ludlamite. Final differentiation requires specialized studies due to the lack of distinct, unique macroscopic features. ## Crystal Forms Maricite crystallizes in the orthorhombic system. It most often forms granular and radial aggregates. Well-formed crystals are extremely rare and appear as small, flattened tablets.

Geological environment

## Genesis Maricite is a low-temperature mineral, forming under reducing conditions. Its main environment of formation is siderite and phosphorite concretions in clay and siltstone sediments. It forms as a result of diagenetic processes. It has also been identified as an accessory mineral in some types of meteorites (e.g., pallasites and chondrites), where it forms under cosmic conditions. ## Mineral Associations This mineral co-occurs with siderite, quartz, pyrite, lazulite, wardite, vivianite, ludlamite, and other rare phosphates. In meteorites, it is associated with olivine, troilite, and phosphate group minerals such as stanfieldite and farringtonite. ## Localities The most important and type locality for maricite is the Big Fish River and Rapid Creek area in Yukon, Canada, where it occurs in famous siderite concretions. It has also been found in the Messel Pit in Germany (in oil shales) and in several localities in the USA. Its presence has also been confirmed in meteorites found in various parts of the world, including the Esquel meteorite (Argentina) and Imilac (Chile).

Rarity

Very rare

For collectors

## Quality Criteria The most prized specimens by collectors are those with well-formed, radial aggregates, clearly visible in a cut and polished siderite concretion. The color contrast between gray or yellowish maricite and the darker host rock enhances the attractiveness of the specimen. Due to the extreme rarity of well-formed crystals, any such specimen, even microscopic, is considered exceptional. ## Popular Localities By far, the most sought-after specimens come from the classic locality in Yukon, Canada. Material from this location is considered reference for the species. Specimens identified in meteorites are rarities of immense scientific and collector value, although they rarely enter the commercial market.

Care and storage

## Cleaning Maricite specimens should be cleaned very carefully, preferably with a soft, dry brush to remove dust. The use of water is not recommended, as the mineral may react with moisture and undergo slow chemical changes. Ultrasonic cleaners should be avoided. ## What to Avoid Avoid contact with water, acids, and other chemicals. Maricite is sensitive to atmospheric conditions, and moisture can accelerate its oxidation and decomposition. It should not be heated or exposed to sudden temperature changes. ## Storage It is recommended to store specimens in dry conditions, preferably in tightly sealed containers or display cases with a desiccant (e.g., silica gel). Display should be in enclosed cabinets, away from direct sunlight and sources of moisture.

Sources

IMA Mineral List (CNMNC)