Guixiangite

Chemical formula: Ni<sup>3+</sup>(BiS)<sup>3-</sup>

Guixiangite is an extremely rare nickel bismuth sulfide, forming microscopic, metallic inclusions in other minerals.

## Characteristics Guixiangite is a mineral with a metallic luster, occurring as extremely small, anhedral (irregularly shaped) grains not exceeding 10-30 micrometers in size. It is observed as inclusions within aurostibite crystals, where it forms irregular aggregates. Its color in reflected light is gray. ## Physical Properties Due to the microscopic size of the grains, most physical properties, such as hardness, density, cleavage, or fracture, have not been determined. The luster is metallic. ## History and Name The mineral was approved by the IMA in 2023 (IMA2023-034). Its name comes from the discovery locality - the Guixiang gold deposit in Guizhou Province, China. It was described by a team of researchers, including Yu-Miao Meng and his collaborators.

Properties

Luster
Metallic
Cleavage
None
Transparency
Opaque
Crystal system
Cubic

Diagnostic features

## Identification Identification of guixiangite is only possible using advanced laboratory techniques, such as electron microprobe analysis (EMPA) in reflected light. Its characteristic feature is its chemical composition - it is the only known natural nickel bismuth sulfide. It occurs as microscopic, gray, anhedral inclusions in aurostibite. ## Distinguishing from similar minerals Distinguishing it from other microscopic sulfides or native metals is impossible without chemical analysis. Its unique chemical composition is a key diagnostic feature. ## Crystal forms Observed exclusively as anhedral, irregular grains and aggregates.

Geological environment

## Genesis Guixiangite forms under hydrothermal conditions. At its type locality (Guixiang deposit), it is associated with gold mineralization within tectonic faults cutting through siltstones and mudstones with limestone interbeds. ## Mineral associations This mineral occurs in close association with aurostibite (as inclusions), native gold, quartz, fluorite, pyrite, arsenopyrite, ullmannite, and native antimony. ## Localities The only confirmed occurrence worldwide is its type locality: Guixiang gold deposit, Zhenfeng County, Qianxinan Buyei and Miao Autonomous Prefecture, Guizhou Province, China.

Rarity

Extremely rare

For collectors

## Quality criteria Guixiangite is not a mineral available on the collector's market in the form of isolated specimens. Its value is purely scientific. Any potential collector's value would pertain to a rich specimen of aurostibite from the Guixiang deposit, in which the presence of guixiangite has been confirmed. In such a case, the quality would be determined by the quality and aesthetics of the main mineral (aurostibite). ## Popular localities The only known and potential source of specimens is the type locality in China.

Care and storage

## Cleaning Due to its extremely small size and occurrence as inclusions, cleaning individual guixiangite grains is impossible. Care applies to the matrix mineral in which it occurs. ## What to avoid Aggressive chemicals, ultrasonics, and sudden temperature changes should be avoided, as they could damage the surrounding aurostibite or other associated minerals. ## Storage Specimens containing guixiangite should be stored under stable conditions, in sealed containers protected from dust and mechanical damage. As a micromineral, it requires proper labeling and storage in specialized boxes.

Sources

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