Kamphaugite-(Y)
Chemical formula: CaY(CO<sub>3</sub>)<sub>2</sub>(OH)·H<sub>2</sub>O
A rare, hydrated calcium yttrium carbonate, forming tiny, colorless or white crystals and radial aggregates.
Properties
- Mohs hardness
- 2-3
- Luster
- Vitreous to pearly
- Streak
- White
- Density
- 3.06
- Cleavage
- Good on {001}
- Fracture
- Uneven
- Transparency
- Transparent to translucent
- Crystal system
- Tetragonal
Diagnostic features
## Identification Characteristic features include radial aggregates composed of tiny, acicular or bladed crystals. The reaction with hydrochloric acid (vigorous effervescence) is a strong diagnostic indicator for a carbonate. Occurrence in nepheline syenite pegmatites in association with rare earth minerals also aids in identification. ## Distinguishing from Similar Minerals It can be confused with other carbonates forming radial aggregates, such as aragonite or natrolite (a silicate). Aragonite is significantly harder (3.5-4). Accurate differentiation from other rare REE carbonates, such as kimuraite-(Y) or lokkaite-(Y), usually requires advanced chemical analyses (EDS/WDS). ## Crystal Forms Crystals are elongated, acicular or bladed, often flattened. They usually occur in radial, stellate, or spherical aggregates. Less commonly, they form rosettes or chaotic groupings.
Geological environment
## Genesis Kamphaugite-(Y) is a hydrothermal mineral. It forms in the late stages of crystallization of nepheline syenite pegmatites, crystallizing in rock fissures and cavities (miaroles) from solutions rich in rare earth elements, especially yttrium. ## Mineral Associations It most often co-occurs with minerals such as: microcline, albite, quartz, aegirine, zircon, as well as other rare earth minerals, e.g., bastnäsite, parisite, synchysite, gadolinite, and fluorite. ## Localities The most important and type locality (localitas typica) are the pegmatites in the Langesundsfjorden area in Norway (e.g., Tveidalen quarry). It is also known from several other localities worldwide, including Mont Saint-Hilaire in Canada (Quebec) and the Pilanesberg alkaline complex in the Republic of South Africa.
Rarity
Very rare
For collectors
## Quality Criteria The most valued by collectors are specimens with well-formed, sharp, and distinct radial aggregates, contrasting with the rock matrix. The size of the aggregates is a key factor – the larger and more complete, the more valuable the specimen. Luster and the absence of damage to the delicate acicular crystals also significantly increase value. ## Popular Localities By far the most sought-after specimens come from the classic localities in Norway, in the Langesundsfjorden area, which are historically most important and have provided the best quality material. Specimens from Mont Saint-Hilaire in Canada are also valued in specialized collections.
Care and storage
## Cleaning Specimens should be cleaned very carefully, only with a soft, dry brush to remove dust. Due to its low hardness and brittleness, ultrasonic cleaners and mechanical cleaning should be avoided. ## What to Avoid Contact with acids must be absolutely avoided, as they cause vigorous effervescence and decomposition of the mineral. As a carbonate, it is very susceptible to them. High temperatures and prolonged exposure to moisture should also be avoided. ## Storage It is recommended to store specimens in closed, stable containers or display cases to protect them from mechanical damage, dust, and sudden changes in humidity. Fragile aggregates require particular caution.