Zugshunstite-(Ce)

Chemical formula: Ce<sup>3+</sup>Al(S<sup>6+</sup>O<sub>4</sub>)<sub>2</sub>((C<sub>2</sub>)<sup>6+</sup>O<sub>4</sub>)·12H<sub>2</sub>O

Zugshunstit-(Ce) is a very rare, hydrated sulfate and oxalate of cerium and aluminum, forming colorless, acicular crystals.

## Characteristics Zugshunstit-(Ce) is a mineral from the sulfate and oxalate group. It occurs as fine, acicular or fibrous crystals, which form radial aggregates, rosettes, or spherulitic clusters. Individual crystals are colorless and transparent, and their small size makes the mineral appear as white, silky, or dull coatings and spheres in aggregates. ## Physical Properties The crystals are flexible and can be bent. The mineral is characterized by a vitreous luster, which transitions to silky in dense aggregates. It is very soft, with a Mohs hardness of approximately 2. The density calculated based on the formula and unit cell parameters is 2.46 g/cm³. ## Colors and Varieties The mineral is colorless, and its aggregates are white. No varieties are distinguished. ## History and Name The mineral's name comes from its discovery locality – the Zug Shuntu uranium mine in Mongolia. The -(Ce) suffix refers to the dominant rare-earth element in its composition – cerium. It was approved as a new mineral by the International Mineralogical Association (IMA) in 1996 (IMA1996-042). It was first described in 1998 by a Russian team of mineralogists. ## Applications Due to its extreme rarity, small crystal size, and occurrence only on a micro scale, zugshunstit-(Ce) has no practical applications. It is solely an object of scientific and collector interest for specialized collectors of rare minerals.

Properties

Mohs hardness
2
Luster
Vitreous
Streak
White
Density
2.46
Cleavage
None
Fracture
Uneven
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Zugshunstit-(Ce) is difficult to identify visually without magnification. Characteristic features include white, radial or spherulitic aggregates composed of very fine, acicular crystals. Its occurrence is limited to specific oxidation zones of uranium deposits. Certain identification requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical microanalysis (EDS). ## Distinguishing from Similar Minerals It can be confused with other secondary sulfate or oxalate minerals forming acicular aggregates, such as gypsum, epsomite, and especially with other oxalates (humboldtine, whewellite). Differentiation is based on chemical analysis (presence of cerium and aluminum) and crystallographic studies. ## Crystal Forms It forms elongated, acicular or fibrous crystals, usually not exceeding 1 mm in length and a few micrometers in thickness. These crystals combine into characteristic radial aggregates, rosettes, and spherulites.

Geological environment

## Genesis It is a secondary mineral, formed in the oxidation (weathering) zones of uranium deposits. Its formation is associated with the interaction of sulfate-rich waters with rocks containing rare-earth elements and organic matter (e.g., coal), which is the source of oxalic acid. ## Mineral Associations It co-occurs with other secondary minerals of the oxidation zone, such as gypsum, jarosite, as well as uranium minerals and rare-earth elements. In its type locality, it was found in association with gypsum, quartz, hematite, and hydromica. ## Localities The only confirmed and described occurrence of this mineral in the world is its type locality – the Zug Shuntu uranium mine in the Dornogovi Aimag of Mongolia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of zugshunstit-(Ce) specimens is primarily assessed based on the richness and aesthetics of the aggregates. The most valued specimens are those with well-formed, distinct spherulites or radial rosettes on a contrasting rock matrix. The size of the aggregates and the absence of damage to the delicate acicular crystals also significantly increase their collector's value. Due to the microscopic nature of the mineral, all specimens fall into the "micromount" category. ## Popular Localities The only source of specimens is the Zug Shuntu mine in Mongolia. Material from this locality is extremely difficult to obtain on the collector's market.

Care and storage

## Cleaning Specimens should be handled with the utmost care. Cleaning is not recommended due to the extreme delicacy of the crystals. If necessary, compressed air can be used from a safe distance to remove loose dust particles. Any contact with water or other liquids should be avoided. ## What to Avoid Contact with water, which can dissolve or damage the mineral, must be strictly avoided. The crystals are very soft and brittle, so touching, vibrations, and ultrasonics should be avoided. It should be protected from chemicals and high temperatures, which can cause the loss of crystallization water. ## Storage It is recommended to store specimens only in sealed, enclosed "micromount" boxes, which protect against mechanical damage, dust, and humidity changes. Exposure should be away from direct sunlight and heat sources.

Sources

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