Strontiofluorite

Chemical formula: SrF₂

Strontiofluorite is a rare halide from the fluorite group, being the strontium analog of fluorite, distinguished by its occurrence in alkaline massifs.

## Characteristics Strontiofluorite is the strontium analog of fluorite, belonging to the same mineral group. It typically forms small, cubic or octahedral crystals, often with rounded edges. It also occurs as granular aggregates or as fillings in small rock cavities. Its appearance is very similar to common fluorite, which makes identification difficult without specialized tests. ## Physical Properties This mineral is characterized by a hardness of 4 on the Mohs scale, meaning it is relatively soft and susceptible to scratching. It has a vitreous luster and is translucent. Its density is approximately 4.05 g/cm³, making it noticeably heavier than most similarly looking minerals. ## Colors and Varieties Typical strontiofluorite specimens are colorless or have a pale gray hue. No distinct color or commercial varieties have been identified. ## History and Name The mineral's name directly refers to its chemical composition – the dominant strontium (strontio) and its belonging to the fluorite group. It was officially recognized as a new mineral by the International Mineralogical Association (IMA) in 2009. The type locality, from which the first described specimens originated, is the Koashva open pit on the Kola Peninsula in Russia. ## Applications Strontiofluorite has no industrial application. Its significance is purely scientific and collectible due to its rarity.

Properties

Mohs hardness: 4
Luster: Vitreous
Streak: white
Density: 4.05
Cleavage: {111}
Fracture: Step-Like
Transparency: Translucent
Crystal system: Isometric

Diagnostic features

## Identification Visual identification of strontiofluorite is very difficult due to its strong resemblance to fluorite. A key feature is its higher density. Certain identification requires advanced analytical methods, such as chemical composition analysis (EDS/WDS) or X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It is most often confused with fluorite (CaF₂). Strontiofluorite is denser than fluorite. It can also be confused with colorless varieties of halite (NaCl), which is significantly lighter, softer, and has a salty taste. ## Crystal Forms It crystallizes in the isometric system, most often forming simple cubes and octahedra. Crystals are usually small and can occur as single individuals or granular aggregates.

Geological environment

## Genesis Strontiofluorite is a hydrothermal mineral, associated with diverse alkaline rock complexes and carbonatites. It forms in the late stages of crystallization, filling voids and fractures in the host rock. ## Mineral Associations It often co-occurs with other rare alkaline minerals such as lamprophyllite, lorenzenite, eudialyte, as well as more common minerals like aegirine, nepheline, microcline, and natrolite. ## Localities The most important and type locality for strontiofluorite is the Khibiny Massif on the Kola Peninsula in Russia, specifically the Koashva open pit. This is the only locality from which well-formed, confirmed specimens of this mineral originate.

Rarity

Very rare

For collectors

## Quality Criteria For collectors, the most desirable specimens are those with well-formed, sharp, and transparent crystals, set on a contrasting rock matrix. Due to its rarity, even small but distinct crystals are considered valuable. Specimens with documented type locality are also highly prized. ## Popular Localities The only source of collectible specimens is the Kola Peninsula in Russia. Specimens from any other locality would be a mineralogical sensation and would require detailed verification.

Care and storage

## Cleaning Specimens should only be cleaned with lukewarm distilled water, using a very soft brush to remove dust. Ultrasonic cleaners should be avoided, as they can damage the crystals. ## What to Avoid The mineral is sensitive to sudden temperature changes and strong acids. Due to its relatively low hardness, it should be protected from contact with harder minerals (e.g., quartz), which can easily scratch it. ## Storage It is recommended to store specimens in separate, padded boxes or on stands in a closed display cabinet, away from heat sources and direct sunlight. Avoid areas with high humidity.