Zhangpeishanite

Chemical formula: BaFCl

Zhangpeishanite is a very rare barium fluoride chloride, forming colorless, platy crystals with a pearly luster.

## Characteristics Zhangpeishanite is an extremely rare mineral from the halide group. It occurs as very small, colorless, thin, platy crystals, reaching sizes up to 0.3 mm. The crystals are transparent and characterized by perfect cleavage, which imparts a pearly luster to the cleavage surfaces. ## Physical Properties This mineral has a hardness of approximately 3 on the Mohs scale. Its density is high, around 4.55 g/cm³. The luster is pearly on cleavage surfaces and vitreous on other surfaces. It is transparent and has a white streak. ## History and Name Zhangpeishanite was named in honor of Zhang Peishan (1926–2010), a mineralogist and professor at the Institute of Geology and Geophysics, Chinese Academy of Sciences, in recognition of his contributions to mineral and deposit research in China. It was discovered in the Saima iron ore deposit in Liaoning Province, China, and approved as a new mineral by the IMA in 2006 (IMA2006-035). ## Uses Due to its extreme rarity and microscopic crystal size, zhangpeishanite has no commercial or industrial applications. Its significance is purely scientific and collectible, being an object of interest for specialized collectors of rare minerals.

Properties

Mohs hardness: 2.5
Color: Colorless
Luster: Pearly, Vitreous
Streak: White
Density: 0
Cleavage: {001} (synthetic)
Fracture: Uneven
Transparency: Transparent
Crystal system: Tetragonal

Diagnostic features

## Identification Field identification of zhangpeishanite is impossible due to its microscopic size. Identification requires advanced laboratory techniques, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS) to confirm its composition (presence of barium, fluorine, and chlorine) and crystal structure. ## Distinguishing from Similar Minerals It can be confused with other colorless, platy microscopic minerals, such as baryte or celestine, but it differs from them in chemical composition (it is a halide, not a sulfate). From matlockite (PbFCl), it is distinguished by the presence of barium instead of lead, which requires chemical analysis. ## Crystal Forms It forms thin, platy crystals with hexagonal or octagonal outlines, often grouped into small aggregates.

Geological environment

## Genesis Zhangpeishanite forms under hydrothermal conditions. In its type locality (Saima deposit), it was found in cavities within alkali-rich rocks that underwent potassic metasomatism. ## Mineral Associations It co-occurs with minerals such as microcline, aegirine, hematite, baryte, calcite, diopside, andradite, and magnetite. ## Localities The only confirmed occurrence of zhangpeishanite in the world is its type locality: the Saima iron ore deposit, near Fengcheng city, in Liaoning Province, northeastern China.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, specimens with sharply defined, well-formed, transparent crystals that are clearly visible on the rock matrix are most highly valued. Rich crystal aggregates are also desirable. Contrast with associated minerals (e.g., dark hematite) enhances the aesthetic value of the specimen. ## Popular Localities All collectible material comes from a single location in the world – the Saima deposit in China. Specimens from this locality are the only ones available to collectors.

Care and storage

## Cleaning Zhangpeishanite specimens, due to their microscopic size and delicacy, should generally not be cleaned mechanically. If cleaning is absolutely necessary, only compressed air should be used from a safe distance to remove dust. ## What to Avoid Avoid contact with water, acids, and other chemicals. The mineral is sensitive to shocks and mechanical damage due to its perfect cleavage. It should not be heated or exposed to sudden temperature changes. ## Storage Specimens should be stored under stable conditions, in specialized "micromount" boxes that protect them from dust, humidity, and physical damage. Avoid vibrations and direct sunlight.