Raslakite
Chemical formula: Na<sub>15</sub>Ca<sub>3</sub>Fe<sup>2+</sup><sub>3</sub>(Na,Zr<sup>4+</sup>)<sub>3</sub>Zr<sup>4+</sup><sub>3</sub>(Si,Nb<sup>5+</sup>)Si<sub>25</sub>O<sub>73</sub>(OH,H<sub>2</sub>O)<sub>3</sub>(Cl,OH)
A very rare silicate from the eudialyte group, distinguished by its pale, yellowish-brown color and occurrence in pegmatites of the Kola Peninsula.
Description
## Characteristics Raslakite is a complex cyclosilicate belonging to the eudialyte group. It occurs as irregular, anhedral grains, usually up to several millimeters in size, embedded in the host rock. It rarely forms imperfectly developed crystals. It is characterized by a pale, yellow to yellowish-brown color and a vitreous luster. It is a transparent mineral. ## Physical Properties Its Mohs hardness is 5 to 6, making it a relatively scratch-resistant mineral. The measured density is approximately 2.91 g/cm³. It does not exhibit cleavage, and its fracture is conchoidal. ## Colors and Varieties This mineral occurs in uniform shades from pale yellow to yellowish-brown. No color or commercial varieties have been distinguished. ## History and Name Raslakite was recognized as a new mineral by the International Mineralogical Association (IMA) in 2003. Its name comes from its discovery locality – the Raslak Cirques in the Khibiny Massif on the Kola Peninsula, Russia. It was described by a team of mineralogists led by Igor V. Pekov. ## Uses Due to its extreme rarity, raslakite has no industrial applications. It is solely an object of scientific interest and a prized acquisition for advanced collections of rare minerals.
Diagnostic features
## Identification Identifying raslakite in the field is practically impossible without specialized equipment. Its main diagnostic features are characteristic mineral parageneses, locality (Khibiny Massif), pale yellow color, and vitreous luster. Definitive identification requires advanced analytical methods such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS). ## Distinction from Similar Minerals Raslakite is visually almost identical to other yellow minerals from the eudialyte group, such as oneillite or georgbarsanovite. Distinguishing them from each other is only possible based on detailed chemical composition analysis, particularly the proportions of sodium, calcium, iron, zirconium, and niobium. ## Crystal Forms It is most commonly found as anhedral (irregular) grains and granular aggregates. Rarely, poorly developed, small crystals with a tabular or short-prismatic habit, typical of the eudialyte group, are observed.
Geological environment
## Genesis Raslakite is a magmatic mineral, crystallizing in the late stages of evolution of highly differentiated, extremely alkaline (ultra-agpaitic) pegmatites. It forms in pegmatite veins cutting rischorrites (a variety of nepheline syenites) in the Khibiny Massif. ## Mineral Associations This mineral occurs in association with other rare alkaline minerals. Its most common associations include aegirine, potassium feldspar, nepheline, sodalite, lamprophyllite, lomonosovite, villiaumite, zirsinalite, and umbite. ## Localities The only confirmed and described occurrence of raslakite in the world is its type locality – the Koashva open-pit mine in the Khibiny Massif, Murmansk Oblast, Kola Peninsula, Russia.
Rarity
Very rare
Collector aspects
## Quality Criteria The collector's appeal of raslakite is primarily determined by its rarity. The most highly valued specimens are those in which raslakite grains are as large as possible, clearly visible, and abundantly present in the host rock. Additional value is provided by the presence of well-formed crystals (although these are extremely rare) and association with other rare minerals from this locality. ## Popular Localities All raslakite specimens available on the collector's market come from a single location in the world: the Koashva mine in the Khibiny Massif, Russia. This is the only source of this mineral.
Care and storage
## Cleaning Raslakite specimens should only be cleaned mechanically, using a soft brush to remove dust. If necessary, distilled water can be used, followed by thorough drying of the specimen. ## What to Avoid Avoid contact with acids and strong chemical agents, which can damage the mineral's surface. Ultrasonic cleaners are not recommended. The mineral is stable in light and normal temperatures, but sudden thermal changes should be avoided. ## Storage It is recommended to store specimens in closed display boxes to protect them from dust and accidental damage. Due to its rarity, avoid exposing it to the risk of scratching by harder minerals.