Burovaite-Ca
Chemical formula: (Na,K)₄Ca₂(Ti⁴⁺,Nb⁵⁺)₈[Si₄O₁₂]₄(OH,O)₈·12H₂O
Burovaite-Ca is a very rare mineral from the silicate group, forming microscopic, yellowish-brown crystals in alkaline pegmatites.
Properties
- Mohs hardness
- 5
- Color
- White
- Luster
- Vitreous
- Streak
- White
- Density
- 2.73
- Cleavage
- Perfect on {100}
- Fracture
- Uneven
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identification of Burovaite-Ca is almost exclusively possible based on chemical analysis (EDS/WDS) and crystallographic analysis (XRD) due to its microscopic size and occurrence in complex parageneses. Visually, it is characterized by its yellowish-brown color and typical radial aggregates of fine, tabular crystals. ## Distinguishing from Similar Minerals It can be confused with other minerals from the labuntsovite group, such as labuntsovite-Mn or gutkovaite-Mn, which often co-occur in the same localities and have a similar appearance. Definitive distinction requires advanced analytical methods to determine the dominance of calcium, sodium, and titanium in the chemical composition. ## Crystal Forms It forms elongated, prismatic or flattened, tabular crystals that combine into characteristic radial or stellate aggregates. Single, well-formed crystals are extremely rare.
Geological environment
## Genesis Burovaite-Ca is a hydrothermal mineral, crystallizing in the late stages of the evolution of agpaitic (highly alkaline) pegmatites. It forms in vugs and fissures within these pegmatites. ## Mineral Associations It most often co-occurs with other rare alkaline minerals, such as natrolite, vinogradovite, labuntsovite-Mn, raite, catapleiite, aegirine, lorenzenite, and analcime. ## Localities This is an extremely rare mineral, known from only a few localities worldwide. The most important and type locality is Mount Njorkpakhk in the Khibiny Massif on the Kola Peninsula, Russia. It has also been identified in the Lovozero Massif (also on the Kola Peninsula) and in the Ilímaussaq complex in Greenland.
Rarity
Extremely rare
For collectors
## Quality Criteria The most highly valued specimens are those showing well-formed, radial aggregates of Burovaite-Ca crystals, clearly distinguished by color from the host rock (matrix). Due to the microscopic nature of the mineral, the quality of the micromount itself is crucial. The size of the aggregates (even if only a few millimeters) and the intensity of the yellow color increase the value of the specimen. ## Popular Localities The only source of collectible specimens is the Khibiny Massif on the Kola Peninsula, Russia. Specimens from other localities are practically non-existent on the market.
Care and storage
## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to the microscopic size of the crystals and their fragility, any form of mechanical or chemical cleaning, including the use of water, is discouraged. ## What to Avoid Avoid contact with all chemicals, acids, and detergents. The crystals are very fragile and susceptible to mechanical damage, ultrasound, and sudden temperature changes. ## Storage Micromount specimens should be stored in specialized, sealed boxes (so-called micromount boxes) to protect them from dust, shocks, and mechanical damage. Avoid exposure to direct sunlight and high humidity.