Fuyuanite

Chemical formula: Mg<sub>7</sub>Nb<sup>5+</sup><sub>6</sub>O<sub>18</sub>(OH)<sub>8</sub>

Fuyuanite is a newly discovered (2023) mineral from the niobate group, forming colorless, microscopic crystals in calcite-dolomite marbles.

## Characteristics Fuyuanite is a hydrated magnesium niobate that forms extremely small, platy crystals up to 100 micrometers in size, usually aggregated into clusters reaching 200 micrometers (0.2 mm). It is a colorless and fully transparent mineral, which, combined with its microscopic crystal size, makes it impossible to observe with the naked eye. It occurs as an inclusion in carbonate rocks. ## Physical Properties The mineral is characterized by a vitreous luster. Its density, calculated based on chemical composition and crystal structure, is 3.73 g/cm³. The Mohs hardness has not yet been determined. It is a brittle mineral. ## Colors and Varieties Fuyuanite is colorless. No colored varieties are known. ## History and Name The mineral's name comes from its discovery locality – the Fuyuan quarry in Shandong Province, China. It was officially approved as a new mineral species by the International Mineralogical Association (IMA) in 2023 under the number IMA 2023-069. ## Applications Due to its extreme rarity and microscopic size, fuyuanite has no commercial or industrial applications. It is solely an object of scientific interest.

Properties

Luster
Vitreous
Streak
White
Density
3.73
Cleavage
Perfect on {010}
Transparency
Transparent
Crystal system
Orthorhombic

Diagnostic features

## Identification Identification of fuyuanite is only possible using advanced analytical techniques, such as energy-dispersive spectroscopy (EDS) to determine chemical composition and X-ray diffraction (XRD) to confirm crystal structure. Visual identification at a macroscopic scale or even under a standard microscope is impossible. ## Distinguishing from Similar Minerals As a colorless, microscopic inclusion, fuyuanite is visually indistinguishable from many other co-occurring minerals, such as calcite, dolomite, forsterite, or diopside. Definitive differentiation requires specialized chemical and structural analysis. ## Crystal Forms It forms thin, platy or bladed crystals that combine into small, rosette-like or irregular aggregates.

Geological environment

## Genesis Fuyuanite forms under conditions of contact metamorphism. It was discovered in calcite-dolomite marbles that underwent alteration due to intruding igneous rocks. ## Mineral Associations This mineral co-occurs with calcite, dolomite, forsterite, diopside, spinel, fluorapatite, and minerals from the pyrochlore group. ## Localities The only confirmed locality of fuyuanite in the world is its type locality – the Fuyuan quarry, in Zaozhuang County, Shandong Province, eastern China.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, fuyuanite is not evaluated according to typical criteria such as color or transparency. The only value for a collector is possessing a specimen of the host rock from the type locality with analytically confirmed presence of fuyuanite. Specimens richer in microscopic aggregates may be considered more valuable. ## Popular Localities The only source of specimens is the Fuyuan quarry in China.

Care and storage

## Cleaning Fuyuanite specimens occur as microscopic inclusions in the host rock (marble), so care applies to the entire specimen. It can be cleaned of dust with a soft brush or compressed air. Careful washing in distilled water is permissible. ## What to Avoid Contact with acids (e.g., hydrochloric acid) should be strictly avoided, as they will rapidly dissolve the surrounding calcite-dolomite marble. The specimen should be protected from ultrasound, high temperatures, and strong mechanical shocks. ## Storage Specimens containing fuyuanite, most often in the form of micromounts, should be stored in closed boxes that protect them from dust and damage. It is not sensitive to light.

Sources

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