Fluorluanshiweiite
Chemical formula: KLiAl<sub>1.5</sub>☐<sub>0.5</sub>(Si<sub>3.5</sub>Al<sub>0.5</sub>)O<sub>10</sub>F<sub>2</sub>
Fluorluanshiweite is a rare mica group mineral, a potassium lithium-aluminum silicate, distinguished by its high fluorine content.
Properties
- Mohs hardness
- 2.5-3
- Luster
- Pearly, Vitreous
- Streak
- White
- Density
- 2.91
- Cleavage
- Perfect on {001}
- Fracture
- Uneven
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Fluorluanshiweite is identified by its micaceous habit – it forms aggregates composed of thin, flexible lamellae with a hexagonal outline. Characteristic features include its silvery-white color, pearly luster on cleavage planes, and very low hardness. It occurs in a specific geological environment – lithium pegmatites. ## Distinguishing from similar minerals It can be confused with other lithium micas, such as lepidolite, polylithionite, or muscovite. It is usually distinguished from lepidolite by the absence of purple coloration. Identification and differentiation from polylithionite, with which it forms a series, require advanced chemical analyses (e.g., EDS/WDS) to determine the exact proportions of lithium, aluminum, and fluorine. Muscovite typically does not contain significant amounts of lithium. ## Crystal forms Crystals have the form of pseudohexagonal tablets and lamellae. They usually occur as platy or scaly aggregates.
Geological environment
## Genesis Fluorluanshiweite is a mineral of magmatic origin, crystallizing in the late stages of the evolution of granite pegmatites rich in lithium and fluorine. It forms under conditions of high activity of volatile elements, especially fluorine. ## Mineral associations At the type locality (Kèkètuōhǎi No. 3 mine, Altai, China), it coexists with quartz, albite, microcline, spodumene, beryl, and tantalite-(Mn). ## Localities The only confirmed and thoroughly described occurrence of this mineral is its type locality – pegmatite No. 3 in the Kèkètuōhǎi (Koktokay) mine in the Altai Prefecture, Xinjiang Autonomous Region, China.
Rarity
Extremely rare
For collectors
## Quality criteria As a newly described and extremely rare mineral, every well-defined specimen is valuable for collectors specializing in mineral systematics or type locality minerals. The most desirable specimens are those with well-formed, hexagonal crystals, clearly visible on the rock matrix. Association with other rare pegmatite minerals is also important. ## Popular localities The only source of specimens is the type locality in China, which makes them extremely difficult to acquire on the collector's market.
Care and storage
## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to its softness and perfect cleavage, contact with water and brushes, which could damage the delicate lamellae, should be avoided. ## What to avoid Contact with chemicals, acids, and detergents should be avoided. The mineral is susceptible to mechanical damage, so it should be protected from scratching, impacts, and bending of the lamellae. It should not be heated or exposed to sudden temperature changes. ## Storage It is recommended to store specimens in closed display boxes, away from dust and moisture. It is best to place it in soft padding material to prevent mechanical damage. It should not be stored in contact with harder minerals.