Fluorlamprophyllite

Chemical formula: (SrNa)Ti₄+₂Na₃Ti₄+(Si₂O₇)₂O₂F₂

Fluorlamprophyllite is a rare titanium and strontium silicate from the lamprophyllite group, distinguished by the presence of fluorine and characteristic platy crystals.

## Characteristics Fluorlamprophyllite is a mineral from the lamprophyllite group, belonging to the silicate class. It forms characteristic tabular or platy crystals, often aggregated into radial or fan-shaped clusters. Its appearance is typical for minerals of this group, with well-developed, flat crystal faces that may exhibit striations. ## Physical Properties This mineral is characterized by a hardness ranging from 5 to 6 on the Mohs scale. It has a vitreous luster, and a greasy or resinous luster on fracture surfaces. It is a relatively dense mineral, with a density of approximately 3.5-3.6 g/cm³. It is brittle and exhibits perfect cleavage in one direction. ## Colors and Varieties Fluorlamprophyllite occurs in shades of brown, from yellowish-brown and reddish-brown to dark brown. No named color varieties or commercial varieties are distinguished. ## History and Name The mineral's name refers to its chemical composition – the dominance of fluorine (Fluor) and its connection to the structural lamprophyllite group (lamprophyllite). It was formally described and recognized by the International Mineralogical Association (IMA) as a distinct mineral species.

Properties

Mohs hardness: 5-6
Luster: Vitreous, Resinous, Greasy
Streak: White
Density: 3.5-3.6
Cleavage: Perfect on {001}
Fracture: Uneven
Transparency: Translucent to opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Fluorlamprophyllite can be identified by its characteristic platy or tabular crystal habit, often forming radial aggregates. Key features include its brown color, vitreous luster, and perfect cleavage in one direction, which causes the mineral to easily split into thin lamellae. ## Distinguishing from Similar Minerals It can be confused with other minerals from the lamprophyllite group, such as lamprophyllite or barytolamprophyllite. Definitive distinction requires advanced chemical analyses (e.g., EDS) to determine the content of fluorine, barium, and strontium. Visually, it may resemble some micas (e.g., biotite), but it is significantly harder and denser than them. ## Crystal Forms Crystals are typically tabular, elongated, and flattened. They often occur as radial or fan-shaped aggregates, as well as intergrown lamellae within the host rock.

Geological environment

## Genesis Fluorlamprophyllite is an igneous mineral, typical of alkaline rock complexes, especially nepheline syenites and associated pegmatites. It forms in the late stages of crystallization of magma rich in elements such as titanium, strontium, sodium, and fluorine. ## Mineral Associations It often co-occurs with other minerals typical of alkaline environments, such as nepheline, microcline, aegirine, eudialyte, lorenzenite, murmanite, and other minerals from the lamprophyllite group. ## Localities The most important and classic localities for fluorlamprophyllite are found on the Kola Peninsula in Russia, within the Khibiny and Lovozero alkaline massifs. These are the main sources of the best-formed specimens of this mineral.

Rarity

Rare

For collectors

## Quality Criteria Specimens with well-formed, sharp crystals, distinct luster, and intense brown color are most valued by collectors. Particularly sought after are radial crystal aggregates, forming aesthetic "suns" or "fans" on a light rock matrix, e.g., in association with nepheline or eudialyte. Large, undamaged crystals are rare. ## Popular Localities Undoubtedly, the most known and prized specimens come from the Khibiny and Lovozero massifs on the Kola Peninsula in Russia. Specimens from these localities set the standard against which other finds are compared.

Care and storage

## Cleaning Fluorlamprophyllite specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, compressed air can be used. Due to its perfect cleavage, mechanical or ultrasonic cleaning is highly risky and may lead to the disintegration of the specimen. ## What to Avoid Avoid contact with acids and other aggressive chemicals. The mineral is brittle and sensitive to impacts and pressure, which can easily cause it to fracture along cleavage planes. It should be protected from sudden temperature changes. ## Storage It is recommended to store specimens in separate, padded collector's boxes to prevent scratches and mechanical damage. Due to its brittleness, it is not suitable for loose storage with other, harder minerals.

Sources

IMA Mineral List (CNMNC)