Lithiomarsturite

Chemical formula: LiCaMn₂+₃Si₅O₁₄(OH)

Lithiomarsturite is a rare lithium, calcium, and manganese silicate, forming pink to reddish-brown, radial aggregates of fibrous crystals.

## Characteristics Lithiomarsturite is a rare mineral from the silicate group, belonging to the rhodonite group. It occurs as clusters of small, fibrous or bladed crystals, which often form radial or spherulitic aggregates. Individual crystals are usually very small, rarely exceeding a few millimeters in length. This mineral is valued by collectors for its attractive pink color and interesting forms of occurrence. ## Physical Properties Lithiomarsturite is characterized by a hardness of approximately 5.5 on the Mohs scale and a density of 3.46 g/cm³. It has a vitreous luster, and its crystals are typically translucent. It exhibits perfect cleavage in two directions. ## Colors and Varieties This mineral occurs in shades from pale pink to reddish-brown. Its color is directly related to the presence of manganese in the crystal structure. No named varieties of lithiomarsturite have been distinguished. ## History and Name Lithiomarsturite was discovered at the Foote Lithium Co. mine in Cleveland County, North Carolina, USA. It was described and approved as a new mineral in 1988 by Donald R. Peacor, Pete J. Dunn, and William B. Simmons. Its name refers to its chemical composition (presence of lithium) and its structural similarity to marsturite.

Properties

Mohs hardness: 5.5
Luster: Vitreous
Streak: White
Density: 3.46
Cleavage: Perfect on {100} and {010}
Fracture: Uneven
Transparency: Translucent
Crystal system: Triclinic

Diagnostic features

## Identification Lithiomarsturite can be identified by its characteristic pink color, fibrous or bladed crystal habit, and radial aggregates. Its occurrence in association with other manganese minerals in pegmatites is also an important diagnostic clue. ## Distinguishing from Similar Minerals It can be confused with rhodonite, which has a similar color but usually forms more massive, compact aggregates and has a slightly higher hardness (5.5-6.5). Pectolite also forms radial aggregates but is usually white or gray and has a different chemical composition. Accurate identification often requires advanced analytical methods, such as X-ray diffraction (XRD). ## Crystal Forms It forms elongated, bladed, or acicular crystals, which almost always occur as radial, stellate, or spherulitic aggregates. Single, well-formed crystals are extremely rare.

Geological environment

## Genesis Lithiomarsturite is a hydrothermal mineral, crystallizing in the late stages of the evolution of complex granitic pegmatites, rich in lithium and manganese. It forms as a result of metasomatism and alteration of earlier manganese minerals. ## Mineral Associations It most commonly co-occurs with minerals such as quartz, microcline, albite, rhodonite, tancoite, triplite, and apatite. In the type locality (Foote mine), it was found in association with rhodonite and quartz. ## Localities The most important and type locality for lithiomarsturite is the Foote Lithium Co. mine in Kings Mountain, Cleveland County, North Carolina, USA. This is the only confirmed locality from which well-characterized specimens of this mineral originate.

Rarity

Very rare

For collectors

## Quality Criteria The most prized lithiomarsturite specimens are those that form well-defined, radial aggregates with an intense pink color. The size of the aggregates and the absence of damage to the delicate, fibrous crystals are also important. Contrast with associated minerals, such as white quartz, can enhance the visual appeal of the specimen. ## Popular Localities The only source of collector specimens is the historic type locality – the Foote mine in North Carolina, USA. This mine is currently inactive and flooded, meaning new specimens are not being acquired, and material on the market comes from old collections.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, distilled water can be used, but prolonged soaking should be avoided. Always dry the specimen thoroughly after cleaning. ## What to Avoid Avoid contact with acids and strong chemicals, which can damage the mineral's surface. Due to its relatively low hardness, it should be protected from scratching by harder minerals. It should not be cleaned in ultrasonic cleaners. ## Storage Lithiomarsturite specimens, especially delicate fibrous aggregates, should be stored in separate, padded boxes to prevent mechanical damage. They should be protected from dust and moisture.

Sources

IMA Mineral List (CNMNC)