Lefontite

Chemical formula: Fe²⁺₂Al₂Be(PO₄)₂(OH)₆

Lefontite is a rare iron, aluminum, and beryllium phosphate, forming small, prismatic crystals of a greenish-gray color.

## Characteristics Lefontite is a very rare mineral from the phosphate group, chemically classified as a hydrated iron, aluminum, and beryllium phosphate. It occurs as small, prismatic crystals up to 1 mm long, often forming radial or rosette-like aggregates. Its color is typically greenish-gray to grayish-green. ## Physical Properties This mineral is characterized by a vitreous luster. It is translucent. Due to the small size of the crystals, many of its physical properties, such as hardness or density, have not yet been precisely determined. ## Colors and Varieties Lefontite occurs in uniform shades of grayish-green and greenish-gray. No color or commercial varieties have been distinguished. ## History and Name The mineral was approved by the IMA in 2018. Its name honors Robert LeFont, an American mineral collector and photomicrographer, in recognition of his contribution to mineralogy. It was first discovered and described in Brazil. ## Uses Lefontite has no industrial application. It is of purely scientific significance and is sought after by specialized collectors of microscopic minerals.

Properties

Luster
Vitreous
Transparency
Translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Identification of lefontite is possible almost exclusively through advanced laboratory methods, such as chemical composition analysis (EDS) and X-ray diffraction (XRD). Visually, at the occurrence site, it can be suspected based on its grayish-green color, radial aggregates, and co-occurrence with other rare phosphates. ## Distinguishing from Similar Minerals It can be confused with other rare, secondary phosphates found in pegmatites, such as eosphorite or rockbridgeite. Definitive differentiation requires specialized analysis. ## Crystal Forms It forms elongated, prismatic crystals that combine into characteristic radial or rosette-like aggregates.

Geological environment

## Genesis Lefontite is a secondary mineral, forming in hydrothermal zones within granitic pegmatites. It crystallizes in small cavities and rock fractures as a result of the alteration of primary phosphate minerals. ## Mineral Associations It co-occurs with other phosphate minerals, such as eosphorite, rockbridgeite, frondelite, as well as with quartz and microcline. ## Localities The only confirmed occurrence of lefontite in the world (type locality) is the João Teodoro Claim in Linópolis (municipality of Divino das Laranjeiras) in the state of Minas Gerais, Brazil.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, lefontite is primarily evaluated based on the quality and development of crystals visible under magnification. The most desirable specimens are those with well-formed, undamaged, radial aggregates that stand out clearly from the host rock. The size of the aggregate and the intensity of the color also increase the specimen's value. ## Popular Localities The only source of specimens is the type locality in Minas Gerais, Brazil, which makes every specimen from there extremely valuable for collectors specializing in rare minerals or minerals from specific localities.

Care and storage

## Cleaning Due to the extreme rarity and small size of the crystals, lefontite specimens should not be cleaned mechanically or chemically. If necessary, a photographic air blower can be used to remove dust. ## What to Avoid Avoid contact with any chemicals, ultrasonics, and sudden temperature changes. The crystals are brittle and susceptible to mechanical damage. ## Storage Specimens should be stored exclusively in specialized micromount boxes, protecting them from dust, vibrations, and light. Display is only possible under a microscope.

External references

Sources

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