Lithiophosphate

Chemical formula: Li₃PO₄

Lithiumphosphate is a rare lithium phosphate, forming colorless or white, tabular crystals and granular aggregates in granitic pegmatites.

## Characteristics Lithiumphosphate is a rare mineral from the phosphate group, chemically being lithium phosphate. It most often occurs as small, tabular or prismatic crystals, which can form radial aggregates. It is also found in the form of granular aggregates. It is usually colorless or white, less often taking on grayish, yellowish, or pinkish hues. Its crystals are characterized by a vitreous luster. ## Physical Properties This mineral has a hardness of approximately 4 on the Mohs scale. It has a vitreous luster, and on fracture surfaces, it can be greasy. It is a relatively light mineral, with a density of about 2.53 g/cm³. It is transparent to translucent. Some specimens may exhibit weak, orange fluorescence under ultraviolet light (both shortwave and longwave). ## Colors and Varieties Lithiumphosphate is most often colorless or white. Impurities can impart delicate shades of gray, yellow, or pink. No named color varieties or commercial varieties are distinguished. ## History and Name The mineral's name, given in 1957 by Mary E. Mrose, comes from its chemical composition – the presence of lithium and the phosphate group. It was first described based on material found at the Foote Lithium Co. mine in the Kings Mountain area, North Carolina, USA. ## Uses Due to its rarity and small crystal size, lithiumphosphate has no industrial application. It is solely an object of interest for collectors specializing in rare minerals, especially those from pegmatites.

Properties

Mohs hardness: 4
Color: White, light pink, colourless
Luster: Vitreous
Streak: White
Density: 2.46
Cleavage: Perfect on {010}, good on {100}
Fracture: Uneven to conchoidal
Transparency: Transparent,Translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Lithiumphosphate is identified based on its occurrence in granitic pegmatites, orthorhombic crystal habit, relatively low hardness (approx. 4), and characteristic vitreous luster. It often forms small, colorless or white tabular crystals. In laboratory conditions, its chemical composition confirms its identity. ## Distinguishing from Similar Minerals Lithiumphosphate can be confused with other colorless or white pegmatitic minerals, such as quartz, albite, or some phosphates. - It differs from quartz by its significantly lower hardness (quartz has a hardness of 7) and perfect cleavage. - It differs from albite (feldspar) by its crystal habit and the absence of twinning characteristic of feldspars, as well as lower hardness. - It differs from amblygonite and montebrasite, which are also lithium phosphates, by its lower density and different crystal habit. ## Crystal Forms It crystallizes in the orthorhombic system. It forms flattened, tabular crystals with a hexagonal or octagonal outline. It also occurs as short prismatic crystals. It often forms radial or fan-shaped aggregates, as well as granular aggregates.

Geological environment

## Genesis Lithiumphosphate is a hydrothermal mineral, crystallizing in the late stages of the formation of complex granitic pegmatites, rich in lithium and phosphorus. It forms as a result of metasomatism or as a product of crystallization from residual fluids. ## Mineral Associations This mineral co-occurs with other minerals typical of lithium pegmatites. It is most often found in association with quartz, albite, microcline, muscovite, spodumene, eucryptite, as well as other phosphates such as amblygonite-montebrasite, apatite, or triphylite-lithiophilite. ## Localities The most important and classic occurrences of lithiumphosphate are: - United States: Foote mine in Kings Mountain, North Carolina (type locality); Custer Mountain mine in Custer, South Dakota. - Canada: Tanco Mine in Bernic Lake, Manitoba - known for well-formed crystals. - Brazil: Minas Gerais and Paraíba states. - Russia: Kola Peninsula, in the massifs of lujaurite and foyaite.

Rarity

Rare

For collectors

## Quality Criteria Specimens with well-formed, sharp, and undamaged crystals of high transparency are most valued by collectors. Groups of crystals forming aesthetic, radial aggregates on a rock matrix are particularly sought after. Crystal size is a key factor - specimens with crystals exceeding a centimeter are considered exceptional. Purity (lack of inclusions and fractures) and absence of mechanical damage significantly increase the value of a specimen. ## Popular Localities Specimens from the Tanco mine in Manitoba (Canada), which yielded sharp, transparent crystals, are considered among the best in the world. Classic, though usually smaller, are specimens from the type locality in Kings Mountain (USA).

Care and storage

## Cleaning Lithiumphosphate specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, compressed air can be used. Due to possible reactivity with acids, all chemical cleaning agents should be avoided. If washing is necessary, use a small amount of distilled water and immediately dry the specimen thoroughly. ## What to Avoid Avoid contact with acids, which can damage the mineral. It should not be heated or subjected to sudden temperature changes. Although it is not particularly sensitive to light, prolonged exposure to intense sunlight is not recommended. Protect it from mechanical damage and scratching by harder minerals. ## Storage Lithiumphosphate is best stored in a separate, padded display box to avoid contact with other minerals that could scratch it. Displaying it in a closed cabinet, protecting it from dust and mechanical damage, is a good solution.