adamsite-(Y)

Chemical formula: NaY(CO₃)₂ · 6H₂O

Adamsite-(Y) is a very rare, hydrated sodium and yttrium carbonate, forming delicate, acicular crystals.

## Characteristics Adamsite-(Y) is a carbonate mineral characterized by its occurrence in the form of delicate, slender, acicular crystals. These crystals often form radial aggregates, rosettes, or spherical clusters, reaching several millimeters in diameter. It is usually colorless to white. Due to its brittleness and perfect cleavage, specimens require very careful handling. ## Physical Properties This mineral is relatively soft, with a Mohs hardness of 3. Its density is low, at 2.27 g/cm³. It has a vitreous luster, and on cleavage surfaces, it exhibits a pearly luster. It is transparent to translucent. It shows perfect cleavage in one plane, which is a characteristic feature. ## Colors and Varieties Adamsite-(Y) occurs exclusively in shades from colorless to milky white. No colored varieties or trade names are known. ## History and Name The mineral was described in 1999 by George Y. Chao, John A. Huminicki, and Terry S. Ercit. Its name honors Frank Dawson Adams (1859–1942), a Canadian geologist and professor at McGill University in Montreal, in recognition of his contributions to the geology of the region where the mineral was discovered. The suffix "-(Y)" indicates that yttrium (Y) is the dominant rare-earth element in its structure. ## Uses Adamsite-(Y) has no industrial applications. It is solely an object of scientific and collecting interest, being a prized acquisition in specialized collections due to its rarity and aesthetic forms.

Properties

Mohs hardness
3
Color
Colourless, white, pale pink, pale purple.
Luster
Vitreous , Pearly
Streak
White
Density
2.27
Cleavage
Perfect on {001}; good on {100}, {010}.
Transparency
Transparent,Translucent
Crystal system
Triclinic

Diagnostic features

## Identification The key diagnostic feature of adamsite-(Y) is its characteristic form – radial aggregates composed of white, acicular crystals. Its low hardness (3 on the Mohs scale), perfect cleavage, and pearly luster on its surfaces are helpful in identification. It reacts with hydrochloric acid, confirming its belonging to carbonates. However, certain identification is mainly possible based on chemical and X-ray diffraction (XRD) analysis. ## Distinguishing from Similar Minerals Adamsite-(Y) can be confused with other white, acicular minerals occurring in the same environment, especially at Mont Saint-Hilaire. The most difficult to distinguish is thomasclarkite-(Y), which has a very similar appearance and chemical composition – distinguishing them without advanced studies is practically impossible. It can also be confused with some zeolites (e.g., natrolite), but zeolites do not react with acid. ## Crystal Forms Crystals are always strongly elongated, acicular. They form characteristic, radial or chaotic aggregates, as well as spherical clusters and delicate coatings on other minerals.

Geological environment

## Genesis Adamsite-(Y) is a secondary mineral, forming under low-temperature hydrothermal conditions. It forms in the late stage of crystallization in vugs (miaroles) and fractures of nepheline syenite pegmatites, which are part of complex alkaline intrusions. ## Mineral Associations This mineral co-occurs with a wide range of other rare minerals typical of the Mont Saint-Hilaire environment. Its most common associations include: thomasclarkite-(Y), mckelveyite-(Y), donnayite-(Y), ewaldite, aegirine, microcline, analcime, catapleiite, and sericite. ## Localities The most important and typical locality for adamsite-(Y) is the Mont Saint-Hilaire alkaline complex (Poudrette quarry) in Quebec, Canada. This is the source of the world's best specimens of this mineral. The occurrence of adamsite-(Y) has also been reported in ultrabasic alkaline massifs on the Kola Peninsula in Russia (Khibiny and Lovozero massifs), but specimens from these localities are much rarer on the collector's market.

Rarity

Very rare

For collectors

## Quality Criteria The most highly valued by collectors are specimens with well-formed, large (for this mineral) and undamaged radial aggregates. The contrasting combination of white adamsite-(Y) needles with a dark matrix, for example with aegirine, significantly enhances the visual appeal and value of the specimen. The presence of other rare associated minerals on the same specimen is also important. ## Popular Localities Virtually all adamsite-(Y) specimens available on the collector's market come from a single locality in the world: the Poudrette quarry in Mont Saint-Hilaire, Quebec, Canada. This locality is known for producing the best and largest crystals of this mineral.

Care and storage

## Cleaning Adamsite-(Y) is an extremely delicate mineral and partially soluble in water. Cleaning should be kept to an absolute minimum. Only very careful removal of dust with a soft brush or a gentle stream of compressed air from a safe distance is permissible. ## What to Avoid Contact with water and other liquids, which can damage or dissolve the crystals, must be strictly avoided. The mineral is sensitive to acids, with which it reacts violently. It should be protected from mechanical damage, shocks, and vibrations due to its softness and perfect cleavage. Storage in a humid environment or under conditions of rapid temperature changes can lead to its degradation. ## Storage It is recommended to store specimens in closed, padded "micromount" boxes, which protect them from dust, mechanical damage, and humidity changes. Display should be in stable environmental conditions, away from direct sunlight and heat sources.

External references

Sources

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