Meifuite

Chemical formula: KFe₂+₆(Si₇Al)O₁₉(OH)₄Cl₂

Meifuit is a rare silicate mineral, closely related to micas, forming small, platy crystals of dark green or black color.

## Characteristics Meifuit is a mineral belonging to the layered silicates, related to zinnwaldite from the mica group. It occurs as very small, hexagonal or irregular, platy crystals, usually not exceeding 0.2 mm. It forms rosette-like aggregates or appears as single, dispersed flakes within the host rock. Its color ranges from dark green to black, and due to the small size of the crystals, its visual features are difficult to observe with the naked eye. ## Physical Properties This mineral is characterized by a vitreous luster and is translucent. It exhibits perfect cleavage in one direction, typical for minerals of the mica group. Its Mohs hardness is approximately 3, and its density has been calculated at 3.25 g/cm³. ## History and Name Meifuit was first described in 2018. Its name honors Professor Meifu Zhou from the University of Hong Kong, in recognition of his contributions to research on magmatic deposits. The mineral was approved by the International Mineralogical Association (IMA) under number 2017-088. The type locality from which it originates is the Baimazhai intrusion in Yunnan Province, China.

Properties

Mohs hardness: 3
Luster: Vitreous
Streak: Pale green
Density: 3.25
Cleavage: Perfect on {001}
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of meifuit is possible only through advanced analytical methods, such as X-ray diffraction (XRD) and electron microprobe analysis (EMPA). Visual identification in the field or even under a microscope is practically impossible due to its similarity to other micas (e.g., biotite) and small crystal sizes. ## Distinguishing from Similar Minerals Meifuit is visually indistinguishable from other dark micas, such as biotite or zinnwaldite, with which it often coexists. Key to differentiation is the determination of its unique chemical composition, particularly high chlorine and iron content with a simultaneous lack of lithium. ## Crystal Forms It forms very small, pseudohexagonal, platy crystals, often grouped into rosette-like aggregates.

Geological environment

## Genesis Meifuit forms in the final stages of magma crystallization within differentiated mafic and ultramafic intrusions. It is a hydrothermal mineral, crystallizing in the presence of volatile components, such as chlorine. ## Mineral Associations This mineral coexists with titanite, apatite, clinochlore, zinnwaldite, phlogopite, pyrite, chalcopyrite, pentlandite, and platinum-group minerals. ## Localities The only confirmed occurrence of meifuit in the world is its type locality - the Baimazhai Ni-Cu-PGE intrusion in Gejiu County, Honghe Prefecture, Yunnan Province, China.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" mineral, the quality of a specimen is primarily determined by the abundance of crystals on the rock matrix and their best possible development, despite their microscopic size. Confirmation of identification by a reputable laboratory is crucial for scientific and collector value. ## Popular Localities The only source of specimens is the type locality in China. Collector material is practically unavailable on the market and is mainly found in institutional and research collections.

Care and storage

## Cleaning Due to its extreme rarity and small crystal size, meifuit specimens typically do not require cleaning and should be left intact as they occur in the host rock. Any attempt at mechanical cleaning may damage the delicate crystals. ## What to Avoid Contact with chemicals, ultrasound, and any cleaning tools should be avoided. Specimens should be protected from dust and mechanical damage. ## Storage It is recommended to store specimens in stable conditions, in enclosed "micromount" boxes, to prevent dust accumulation and protect against accidental damage. Exposure to shocks and vibrations should be avoided.

Sources

IMA Mineral List (CNMNC)