Chiluite

Chemical formula: Bi<sup>3+</sup><sub>3</sub>Te<sup>6+</sup>Mo<sup>6+</sup>O<sub>10.5</sub>

Chiluite is an extremely rare bismuth, tellurium, and molybdenum oxide, forming microscopic, hexagonal crystals with a metallic luster.

## Characteristics Chiluite is an oxide mineral distinguished by its complex chemical composition containing bismuth, tellurium, and molybdenum. It occurs as extremely small, hexagonal, tabular crystals, reaching sizes up to 20 micrometers. These crystals form aggregates or appear as single flakes. Due to its microscopic size, its visual features are difficult to observe without specialized equipment. ## Physical Properties Chiluite crystals are too small to allow for standard examination of their hardness, density, or other physical properties. The mineral is opaque and exhibits a metallic luster. Its streak is black. ## Colors and Varieties Chiluite is black. No varieties are known. ## History and Name The mineral's name comes from its discovery locality – the Chiluite mine in Henan Province, China. It was first described by Jing-ke Li and collaborators and subsequently approved by the International Mineralogical Association (IMA) in 2020 (IMA2020-038).

Properties

Luster
Metallic
Streak
Black
Transparency
Opaque
Crystal system
Hexagonal

Diagnostic features

## Identification Identification of chiluite is only possible using advanced analytical methods, such as scanning electron microscopy (SEM) with chemical composition analysis (EDS) and X-ray diffraction (XRD). Visual identification, even under a microscope, is impossible without chemical confirmation. ## Differentiation from Similar Minerals Chiluite may be confused with other fine-grained, black minerals with a metallic luster that co-occur in the same environment, e.g., molybdenum or bismuth oxides. Certain differentiation requires specialized elemental analysis. ## Crystal Forms The mineral forms very small, hexagonal crystals with a tabular habit, often gathered in small aggregates.

Geological environment

## Genesis Chiluite forms in the oxidation zones of molybdenum-bismuth deposits. Its genesis is associated with the weathering of primary ores in the presence of tellurium. ## Mineral Associations This mineral co-occurs with quartz, molybdenite, bismuthinite, and other rare oxides and tellurides in the oxidation zone. ## Localities The only confirmed locality for chiluite worldwide is its type locality – the Chiluite mine, in Luanchuan County, Henan Province, China.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, chiluite is not evaluated according to typical aesthetic criteria such as color or size. The collector's value of a specimen lies in its extreme rarity and the scientific confirmation of the mineral's presence on the rock matrix. The most valuable samples are those with the richest concentrations of tiny crystals, well-documented analytically.

Care and storage

## Cleaning Due to the extremely small size of the crystals and their rarity, chiluite specimens should not be cleaned by any mechanical or chemical means. Any attempts at cleaning may lead to irreversible damage to the mineral. ## What to Avoid Avoid contact with chemicals, ultrasound, sudden temperature changes, and all forms of physical impact (abrasion, scratching). ## Storage Chiluite specimens should be stored exclusively in specialized, sealed "micromount" boxes, protecting them from dust, moisture, and mechanical damage. They should be kept under stable room conditions.

Sources

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