Labuntsovite-Mg
Chemical formula: Na<sub>4</sub>K<sub>4</sub>Mg<sub>2</sub>Ti<sup>4+</sup><sub>8</sub>O<sub>4</sub>(Si<sub>4</sub>O<sub>12</sub>)<sub>4</sub>(OH)<sub>4</sub>·10-12H<sub>2</sub>O
Labuntsovite-Mg is a rare mineral from the labuntsovite group, forming small, prismatic crystals with a vitreous luster, found in alkaline massifs.
Properties
- Mohs hardness
- 6
- Luster
- Vitreous
- Streak
- White
- Density
- 2.95
- Cleavage
- Good on {100}
- Fracture
- Uneven
- Transparency
- Transparent to Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Labuntsovite-Mg is identified by its characteristic crystal habit – elongated, prismatic, or acicular, often forming radial aggregates. Key features also include vitreous luster, occurrence in cavities in alkaline rocks, and associations with other rare minerals. ## Distinguishing from Similar Minerals It can be confused with other minerals from the labuntsovite group (e.g., labuntsovite-Mn, kuzmenkoite-Mn), from which differentiation is practically only possible through chemical analysis (EDS/WDS). Some zeolites (e.g., natrolite) may have a similar appearance, but they are usually less hard and have a slightly different luster. ## Crystal Forms Crystals are monoclinic, prismatic in habit, often strongly elongated along the b-axis, even to acicular forms. They usually form radial, stellate, or chaotically tangled aggregates in vugs and fissures.
Geological environment
## Genesis Labuntsovite-Mg is a hydrothermal mineral, crystallizing in the late stages of the evolution of alkaline massifs, such as nepheline syenites and associated pegmatites. It forms in cavities and fissures, often as one of the last minerals to crystallize. ## Mineral Associations This mineral co-occurs with a wide range of other minerals typical of alkaline pegmatites. The most common associations include aegirine, natrolite, analcime, microcline, eudialyte, lorenzenite, catapleiite, as well as other minerals from the labuntsovite group. ## Localities The most important and well-documented occurrences of labuntsovite-Mg are in Russia, on the Kola Peninsula. These are primarily the Khibiny alkaline massifs (Mount Kukisvumchorr, Mount Yukspor) and the Kovdor Massif. Outside Russia, its occurrence has also been reported in the Ilímaussaq complex in Greenland.
Rarity
Rare
For collectors
## Quality Criteria Specimens with well-formed, sharp, and undamaged crystals, forming aesthetic, radial aggregates, are most valued by collectors. High luster and transparency of the crystals are important. A contrasting matrix, e.g., with dark aegirine, significantly enhances the visual appeal of the specimen. Due to the small size of the crystals, it is primarily a mineral sought after for micromount collections. ## Popular Localities By far the most desirable specimens come from the classic localities on the Kola Peninsula in Russia, especially from Khibiny. Specimens from these localities are considered reference material for this mineral.
Care and storage
## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. Brief rinsing in distilled water is permissible, followed by thorough drying. Ultrasonic cleaners should be avoided, as they can damage delicate crystals. ## What to Avoid The mineral is sensitive to strong acids and bases. Prolonged exposure to moisture and sudden temperature changes should be avoided. Due to its fragility, specimens must be protected from impacts and vibrations. ## Storage It is recommended to store specimens in stable conditions, in closed boxes or display cases, to protect them from dust and mechanical damage. It is a typical mineral for micromount collections, so it is often stored in small, dedicated boxes.