Lusernaite-(Y)
Chemical formula: Y<sub>4</sub>Al(CO<sub>3</sub>)<sub>2</sub>(OH,F)<sub>11</sub>·6H<sub>2</sub>O
An extremely rare carbonate mineral, forming colorless, hexagonal crystals in gneiss cavities from Luserna, Italy.
Description
## Characteristics Lusernaite-(Y) is a hydrated aluminum and yttrium carbonate, belonging to the group of very rare minerals. It forms characteristic, thin, platy crystals with a hexagonal outline, which often combine into rosette-like or spherical aggregates. Individual crystals rarely exceed 1 mm in diameter. It is colorless to white and transparent. ## Physical Properties The luster is pearly on expected cleavage surfaces (basal plane of the crystal) and vitreous on other faces. The calculated density is approximately 3.10 g/cm³. Hardness has not been determined due to the small size and fragility of the crystals. ## Colors and Varieties The mineral is colorless or white. No colored or commercial varieties have been distinguished. ## History and Name It was recognized as a new mineral species by the International Mineralogical Association in 2013. Its name comes from the rock in which it was found - "Pietra di Luserna" (Luserna Stone), a local building material. The "-(Y)" suffix indicates the dominance of yttrium among the rare earth elements in its composition. The type locality and only known occurrence is the Vottero quarry in Luserna San Giovanni, Piedmont, Italy. ## Uses Due to its extreme rarity and small crystal size, lusernaite-(Y) has no industrial applications. It is solely an object of scientific and collecting interest, being a valuable acquisition for specialized micromineral collections.
Diagnostic features
## Identification Characteristic features of lusernaite-(Y) include its unique form - thin, hexagonal plates forming rosette-like aggregates - and its occurrence. Colorless or white color, pearly-vitreous luster, and transparency are also helpful. Final identification is only possible using advanced analytical methods, such as X-ray diffraction (XRD) and chemical microanalysis (EDS). ## Distinguishing from Similar Minerals It can be confused with other colorless, platy minerals found in similar environments, such as some micas or other rare carbonates (e.g., synchysite-(Y)). However, synchysite-(Y) is often more yellowish and has a different crystal structure. Due to its rarity and small size, amateur identification is practically impossible. ## Crystal Forms Crystals are in the form of thin, hexagonal plates. They usually occur as radial or spherical aggregates resembling roses or fans, with a diameter of up to several millimeters.
Geological environment
## Genesis Lusernaite-(Y) forms in the final, low-temperature stage of hydrothermal processes. It crystallizes in small cavities (miaroles) within orthogneiss, known as "Luserna Stone." ## Mineral Associations This mineral co-occurs with cavity-forming minerals such as albite, calcite, chamosite, laumontite, malachite, titanite, and synchysite-(Y). It grows directly on the rock-forming minerals of the gneiss, mainly quartz and feldspars. ## Localities The only confirmed and described occurrence in the world is the "Vottero" quarry in Luserna San Giovanni, Piedmont region, Italy.
Rarity
Extremely rare
Collector aspects
## Quality Criteria The quality of micromineral specimens is assessed based on several criteria. The sharpness and development of the hexagonal crystals, as well as the completeness and aesthetics of the rosette-like aggregates, are most important. Specimens where lusernaite-(Y) is abundant and forms well-defined clusters on a small rock matrix are more highly valued. The presence of other rare associated minerals also increases its value. ## Popular Localities All known specimens to collectors come from a single location in the world - the Vottero quarry in Italy, which is the type locality for this mineral.
Care and storage
## Cleaning Lusernaite-(Y) specimens are extremely delicate and fragile. Only compressed air should be used from a safe distance to remove dust. Mechanical cleaning with brushes is not recommended. Contact with water should be as brief as possible and avoided if not absolutely necessary. ## What to Avoid As a carbonate, the mineral is sensitive to acids, with which it reacts violently. All shocks, vibrations, and cleaning in ultrasonic cleaners should be avoided. The crystals are very brittle. ## Storage The safest way to store specimens is to place them in a sealed, padded "micromount" box, which protects against dust, mechanical damage, and sudden changes in humidity.