Yulinite

Chemical formula: SrNb₅+₂O₆

A very rare strontium niobium oxide from the aeschynite group, discovered in the famous Chinese Bayan Obo rare earth element deposit.

## Characteristics Yulinite is an extremely rare oxide mineral belonging to the aeschynite group. Chemically, it is a strontium niobium oxide. It was identified in the form of microscopic grains and crystals, which is typical for many rare mineral phases discovered in modern mineralogy within rare earth element deposits. ## Physical properties Due to its extreme rarity and microscopic crystal size, most of the physical properties of yulinite are difficult to observe macroscopically. The mineral crystallizes in the monoclinic system. ## Colors and varieties The mineral has no known varieties. It forms dark, inconspicuous grains typical of complex niobium oxides. ## History and name The mineral was officially approved by the International Mineralogical Association (IMA) in 2014 (code IMA2014-086). Its name honors Chinese mineralogist Yulin Lin (b. 1935), in recognition of his long-standing contribution to the mineralogical research of the famous Bayan Obo deposit. The type locality is the West Mine within this deposit in Inner Mongolia. ## Uses Due to its microscopic quantities and occurrence limited to a single location worldwide, yulinite has no industrial application. It remains purely an object of scientific interest and of highly specialized collectors of rare minerals.

Properties

Crystal system: Monoclinic

Diagnostic features

## Identification Macroscopic identification of yulinite is practically impossible due to its rarity and similarity to other dark niobium, tantalum, and titanium oxides. Definitive identification requires advanced analytical studies, such as X-ray diffraction (XRD) and electron probe microanalysis (EPMA). ## Distinguishing from similar minerals Visually, this mineral is indistinguishable from other members of the aeschynite group, as well as from columbite, pyrochlore, or other complex oxides occurring in the Bayan Obo deposit. ## Crystal habits It crystallizes in the monoclinic system. It typically forms very fine, microscopic crystals or irregular grains embedded in the matrix rock.

Geological environment

## Origin Yulinite forms in a specific geological environment associated with carbonatites and complex hydrothermal-metasomatic processes. These processes led to the formation of the giant rare earth element, iron, and niobium deposit in Bayan Obo. ## Mineral associations It occurs in paragenesis with other minerals typical of the Bayan Obo deposit, including numerous rare minerals of niobium, titanium, strontium, and rare earth elements. ## Localities The only confirmed locality (locus typicus) is the West Mine within the Bayan Obo deposit (Bayan Obo Mining District, Baotou Prefecture, Inner Mongolia, China).

Rarity

Extremely rare

For collectors

## Quality criteria Yulinite is a mineral of exclusively systematic and scientific importance. For collectors, what matters most is the confirmed origin from the Bayan Obo deposit and the presence of the mineral on the matrix rock. Due to identification difficulties, specimens accompanied by documentation from analytical studies (e.g., an EDS/WDS spectrum) are the most highly valued. ## Famous localities The only source of specimens of this mineral is the West Mine in the Bayan Obo deposit in China.

Care and storage

## Cleaning Specimens containing yulinite should be cleaned exclusively using distilled water and a soft brush. Ultrasonic cleaning should be avoided, as it could damage the microscopic crystals or the fragile matrix rock. ## What to avoid Contact with strong acids and alkalis should be avoided, as they can react with co-occurring minerals in the rock (e.g., carbonates typical of a carbonatite environment). ## Storage Specimens should be stored in a dry environment, preferably in sealable micromount boxes, which protects them from dust, moisture, and accidental mechanical damage.

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External references

https://www.mindat.org/min-499618.html