Gagarinite-(Y)
Chemical formula: NaCaYF₆
Gagarinite-(Y) is a rare fluoride of sodium, calcium, and yttrium, forming hexagonal crystals with a vitreous luster, prized by collectors of rare minerals.
Properties
- Mohs hardness
- 4.5
- Luster
- Vitreous
- Streak
- White
- Density
- 4.11
- Cleavage
- Distinct in one direction, prismatic
- Transparency
- Transparent,Translucent
- Crystal system
- Hexagonal
Diagnostic features
## Identification Helpful features for identifying gagarinite-(Y) include its hexagonal crystal form (if visible), relatively high density, vitreous luster, and occurrence in a specific geological environment – alkaline pegmatites and metasomatites. It reacts with acids. ## Distinguishing from Similar Minerals Gagarinite-(Y) is sometimes confused with other minerals of similar appearance and occurrence environment, such as fluorite, some feldspars, or quartz. It differs from quartz and feldspars by its lower hardness and significantly higher density. It differs from fluorite by its crystal habit (hexagonal instead of cubic or octahedral) and distinct cleavage in one direction. ## Crystal Forms Gagarinite-(Y) crystals have a hexagonal prismatic habit, often terminated by flat faces. It typically forms intergrown, granular, or massive aggregates within the host rock. Well-formed, freestanding crystals are very rare.
Geological environment
## Genesis Gagarinite-(Y) is a mineral of hydrothermal and metasomatic origin. It forms in the late stages of crystallization in alkaline pegmatites, carbonatites, and in sodium metasomatites (albitites) associated with alkaline granites and syenites. ## Mineral Associations This mineral often co-occurs with other rare earth minerals and minerals typical of alkaline rocks. The most common associations include: quartz, microcline, albite, riebeckite, aegirine, pyrochlore, bastnäsite, fluorite, and zircon. ## Localities The most important and type locality for gagarinite-(Y) is the Verkhnee Espe massif in the Tarbagatai Mountains, Kazakhstan. Significant specimens also come from the Strange Lake complex on the border of Quebec and Labrador in Canada, from the Pikes Peak complex in Colorado (USA), and from some pegmatites in Norway and Russia (Kola Peninsula).
Rarity
Rare
For collectors
## Quality Criteria Specimens with well-formed, sharp crystals of distinct hexagonal habit are most highly valued by collectors. Intense color (especially pink or yellow) and transparency are also important. Specimens where gagarinite-(Y) is exposed on a rock matrix in association with other rare minerals are particularly sought after. ## Popular Localities The best localities for this mineral are considered to be its type locality in Kazakhstan and the Strange Lake locality in Canada, which yield some of the largest and best-formed crystals. Specimens from Pikes Peak in the USA are also highly regarded by collectors.
Care and storage
## Cleaning Gagarinite-(Y) specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, distilled water can be used, but prolonged soaking should be avoided. After wet cleaning, the specimen should be thoroughly dried. ## What to Avoid The mineral is sensitive to strong acids. Ultrasonic cleaners and steam cleaning should be avoided, as they can cause cracks. Due to its relatively low hardness, it should be protected from scratching by harder minerals (e.g., quartz). ## Storage It is recommended to store gagarinite-(Y) in a separate, padded display box to avoid contact with other minerals and the risk of mechanical damage. It is not sensitive to light, but extreme temperature changes should be avoided.