Yangzhumingite

Chemical formula: KMg<sub>2.5</sub>Si<sub>4</sub>O<sub>10</sub>F<sub>2</sub>

Yangzhumingite is a rare mineral from the mica group, a potassium and magnesium silicate, distinguished by its colorless, transparent, platy crystals.

## Characteristics Yangzhumingite is a mineral belonging to the mica group. It forms thin, platy or tabular crystals, often gathered into small aggregates. It is colorless and transparent, with a vitreous luster, and a pearly luster on cleavage surfaces. Its crystals are typically small, reaching up to 1 mm in diameter and about 0.05 mm in thickness. ## Physical Properties This mineral is characterized by a hardness ranging from 2.5-3 on the Mohs scale, making it relatively soft. It has perfect cleavage in one direction, typical for micas, which causes it to easily split into thin, flexible lamellae. Its density is approximately 2.84 g/cm³. ## Colors and Varieties Yangzhumingite is colorless. No colored varieties have been distinguished. ## History and Name The mineral's name honors Yang Zhuming (born 1963), a professor of mineralogy and crystallography at the Institute of Geochemistry in Guangzhou, Chinese Academy of Sciences, for his contributions to research on minerals of the mica group. It was approved as a new mineral by the IMA in 2009 (IMA2009-048), and its description was published in 2011. ## Uses Due to its extreme rarity and small crystal size, yangzhumingite has no industrial applications. It is solely an object of scientific and collecting interest for specialized collectors of rare minerals.

Properties

Mohs hardness
2.5-3
Luster
Vitreous, Pearly
Streak
White
Density
2.84
Cleavage
Perfect on {001}
Fracture
Micaceous
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Yangzhumingite is identified based on its appearance – colorless, transparent, thin lamellae with a pearly luster, characteristic of micas. Its occurrence in a specific geological environment (dolomitic marbles) is a key indicator. However, final identification requires advanced analytical methods, such as chemical analysis (EDS/WDS) and X-ray powder diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other colorless micas, such as muscovite or phlogopite. Distinguishing it from them with the naked eye is practically impossible. Yangzhumingite is characterized by a unique chemical composition, particularly a high content of magnesium and fluorine with a simultaneous absence of aluminum in the structure, which is a diagnostic feature confirmed in the laboratory. ## Crystal Forms The crystals have the form of thin, hexagonal plates or lamellae. They occur as single, dispersed crystals or small, loose aggregates.

Geological environment

## Genesis Yangzhumingite forms under conditions of high-grade contact metamorphism. It was discovered in dolomitic marbles that were subjected to ultra-high temperatures in the contact zone with a granitic intrusion. ## Mineral Associations This mineral coexists with minerals such as dolomite, calcite, forsterite, chondrodite, spinel, graphite, and phlogopite. ## Localities The only confirmed worldwide occurrence (type locality) is the Xianghualing mine in Linwu County, Chenzhou Prefecture, Hunan Province, China.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a specimen depends on the size and perfection of the hexagonal crystals, their transparency, and their aesthetic arrangement on the rock matrix (most often on dolomite). Due to its extreme rarity, every, even the smallest, well-identified specimen is valuable for specialized collectors. ## Popular Localities The only source of specimens is the Xianghualing mine in China, which is the type locality for this mineral.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using compressed air to remove dust. Due to its softness and perfect cleavage, contact with water and brushes, which could damage the delicate lamellae, should be avoided. ## What to Avoid All chemicals, ultrasonics, and sudden temperature changes should be avoided. The crystals are very soft and brittle, susceptible to scratching and delamination. They should be protected from moisture. ## Storage It is recommended to store specimens in sealed, padded "micromount" boxes to protect them from mechanical damage, dust, and humidity changes. They should not be exposed to direct sunlight.

Sources

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