Moxuanxueite
Chemical formula: NaCa₆Zr⁴⁺(Si₂O₇)₂OF₃
Moxuanxueite is a rare silicate from the wöhlerite group, distinguished by its light yellow color and occurrence in skarns in China's Yunnan province.
Properties
- Mohs hardness
- 5.5-0
- Luster
- Vitreous
- Streak
- white
- Density
- 3.231
- Cleavage
- distinct {110}
- Fracture
- Conchoidal
- Transparency
- Transparent,Translucent
- Crystal system
- Triclinic
Diagnostic features
## Identification Identification of moxuanxueite is based on its characteristic yellow color, tabular crystal habit, occurrence, and associated minerals. Distinct cleavage and a hardness of 5.5 are also helpful features. However, final confirmation requires advanced analytical methods, such as chemical analysis (EDS) or X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other minerals from the wöhlerite group or other yellow silicates occurring in skarns. Distinguishing it from wöhlerite, lavenite, or hiortdahlite is mainly possible based on precise chemical composition analysis, especially the content of sodium, calcium, and zirconium. ## Crystal Forms Crystals are typically tabular or bladed, often flattened. They form radial or irregular aggregates. They occur as embedded crystals in the rock matrix.
Geological environment
## Genesis Moxuanxueite forms as a result of metasomatic processes within skarns. Its formation is associated with the interaction of zirconium- and fluorine-rich hydrothermal solutions with carbonate rocks (limestones or dolomites) in contact zones with granitoid intrusions. ## Mineral Associations This mineral co-occurs with other minerals typical of skarns, such as diopside, garnets (andradite), fluorite, cassiterite, magnetite, and also with other rare zirconium silicates. ## Localities The only confirmed locality of moxuanxueite in the world is its type locality: the Gejiu polymetallic ore field in Honghe Prefecture, Yunnan Province, China.
Rarity
Very rare
For collectors
## Quality Criteria The most valuable moxuanxueite specimens are those with well-formed, sharp crystals of intense yellow color, set on a contrasting rock matrix. Due to the small size of the crystals, specimens with visible, distinct aggregates are particularly prized. The presence of rare associated minerals is also important. ## Popular Localities The only source of specimens is the type locality in Gejiu, China, which makes them highly sought after by collectors specializing in rare, systematic minerals and those from specific localities (so-called "locality collecting").
Care and storage
## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. Due to the lack of detailed data on reactivity, the use of water or chemical agents is not recommended. ## What to Avoid Avoid contact with acids and other chemicals. The mineral is relatively brittle, so it must be protected from impacts and scratching. There is no data on its sensitivity to light or temperature, but standard caution is advised. ## Storage The safest way to store specimens is to place them in a closed display box, lined with soft material, to prevent mechanical damage and dust accumulation.