Lemmleinite-K

Chemical formula: Na₄K₈Ti₄+₈(Si₄O₁₂)₄(O,OH)₈·₈H₂O

Lemmleinite-K is a rare mineral from the zirsilite group, forming small, tabular crystals with a vitreous luster, found in alkaline pegmatites.

## Characteristics Lemmleinite-K is a complex silicate of titanium, sodium, and potassium, belonging to the zirsilite group. It occurs as very small, thin, tabular or bladed crystals, rarely exceeding 1 mm in length. Crystals often form radial or chaotic aggregates and clusters. Due to their small size, its visual features are difficult to observe without magnification. ## Physical Properties The mineral has a hardness of approximately 5 on the Mohs scale. It has a vitreous luster and is brittle. The calculated density is about 2.85 g/cm³. ## Colors and Varieties Lemmleinite-K is colorless to white, sometimes with a pale yellow or light brown tint. It does not have defined color varieties or commercial names. ## History and Name The mineral's name refers to its chemical composition – it is the potassium (K) analogue of lemmleinite-Ba. It was approved as a new mineral by the IMA in 2000. It was described based on material from the Khibiny Massif on the Kola Peninsula in Russia. ## Uses Lemmleinite-K has no industrial application. It is solely an object of interest for collectors specializing in rare minerals (so-called micromounts) and scientists.

Properties

Mohs hardness: 5
Luster: Vitreous
Streak: White
Density: 2.85
Cleavage: Perfect on {010}, good on {100}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Identification of lemmleinite-K is almost exclusively possible using advanced analytical methods, such as Raman spectroscopy or chemical analysis (EDS/WDS). Visual identification in the field or even in a collection is impossible due to its small size and similarity to many other rare silicates. ## Distinguishing from Similar Minerals It can be confused with other minerals from the zirsilite group (e.g., lemmleinite-Ba, zirsilite), as well as with many other white or colorless minerals found in alkaline pegmatites (e.g., elpidite, lorenzenite). Differentiation requires specialized chemical analysis. ## Crystal Forms It forms very small, thin, tabular or bladed crystals, often grouped into radial aggregates, rosettes, or irregular clusters on the surface of other minerals.

Geological environment

## Genesis Lemmleinite-K is a hydrothermal mineral, crystallizing in the late stages of evolution of highly differentiated alkaline pegmatites, rich in sodium, potassium, and titanium. ## Mineral Associations It most commonly co-occurs with microcline, nepheline, aegirine, lorenzenite, eudialyte, lamprophyllite, lomonosovite, sphalerite, and natrolite. ## Localities The most important and well-documented occurrences of this mineral are in Russia, within the alkaline massifs on the Kola Peninsula (Khibiny Massif and Lovozero Massif). Outside Russia, its occurrences have been reported in Canada (Mont Saint-Hilaire, Quebec).

Rarity

Very rare

For collectors

## Quality Criteria The collector's appeal of a specimen depends on the abundance and development of crystals, even if they are microscopic in size. Specimens with well-defined, radial aggregates on a contrasting background (e.g., on dark aegirine) are most valued. Association with other rare minerals is also important. ## Popular Localities The most famous and prized specimens come from the Khibiny Massif and Lovozero Massif on the Kola Peninsula in Russia. Specimens from Mont Saint-Hilaire in Canada are also sought after by collectors specializing in minerals from this locality.

Care and storage

## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to the extreme delicacy and small size of the crystals, any mechanical contact, including with water or brushes, should be avoided. ## What to Avoid Avoid contact with chemicals, ultrasound, and sudden temperature changes. The crystals are very brittle and easily susceptible to mechanical damage. ## Storage It is recommended to store specimens exclusively in specialized micromount boxes to protect them from dust, vibrations, and damage. They should not be exposed to direct sunlight, although its light sensitivity is not known.

Sources

IMA Mineral List (CNMNC)