Kozoite-(Nd)

Chemical formula: NdCO<sub>3</sub>(OH)

Kozoite-(Nd) is a rare mineral from the carbonate group, forming microscopic, spherulitic aggregates of a pinkish-violet color.

## Characteristics Kozoite-(Nd) is a hydrated neodymium carbonate, belonging to the rare earth mineral group. It occurs as very fine, spherulitic or spherical aggregates, rarely exceeding 0.1 mm in diameter. Individual crystals within these aggregates are lath-like or fibrous. Due to the microscopic size of the crystals, its visual characteristics are difficult to observe without specialized equipment. ## Physical Properties Kozoite-(Nd) crystals exhibit a vitreous luster. The mineral is transparent to translucent. Its hardness and density have not been precisely measured due to its small size and rarity, however, the density calculated based on the chemical formula and unit cell parameters is approximately 4.96 g/cm³. ## Colors and Varieties This mineral is characterized by a pale, pinkish-violet color. No varieties have been distinguished. ## History and Name Kozoite-(Nd) was first described in 2003 by Ritsuro Miyawaki and co-workers. Its name honors Professor Kozo Nagashima (1925–1985), a Japanese chemist from the University of Tsukuba, who specialized in the chemistry of rare earth elements. The suffix "-(Nd)" in the name indicates the dominant rare earth element in its composition, which is neodymium (Nd), according to Levinson's nomenclature from 1966. It was approved as a new mineral species by the International Mineralogical Association (IMA) under number IMA2002-004. ## Uses Kozoite-(Nd) has no practical applications. It is solely an object of scientific and collecting interest due to its rarity and chemical composition.

Properties

Luster
Vitreous
Streak
White
Density
4.96
Cleavage
Perfect on {010}
Transparency
Transparent to translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Identification of kozoite-(Nd) is possible only through advanced laboratory methods, such as X-ray diffraction (XRD) and chemical microanalysis (e.g., EDS/WDS). Visually, it is practically impossible. Under laboratory conditions, its reaction with hydrochloric acid (HCl) is characteristic – it effervesces vigorously, which is typical for carbonates. ## Distinguishing from Similar Minerals It can be confused with other minerals from the ancylite group or other rare earth carbonates, such as bastnäsite or parisite. Differentiation requires specialized chemical analysis to determine the dominant rare earth element and analysis of the crystal structure. ## Crystal Forms It forms spherulitic (spherical) aggregates composed of radially arranged, lath-like or fibrous crystals. Individual, well-formed crystals are not observed.

Geological environment

## Genesis Kozoite-(Nd) is a secondary mineral, formed in the late stages of hydrothermal processes within syenite pegmatites. It forms in rock cavities and fissures as a result of alterations of earlier rare earth minerals. ## Mineral Associations This mineral occurs in association with other, often rare, minerals. In its type locality (Matsushiro, Japan), it was found in association with aegirine, microcline, quartz, eudialyte, as well as secondary minerals such as caysichite-(Y), kimuraite-(Y), lokkaite-(Y), bastnäsite-(Ce), and lanthanite-(Nd). ## Localities The only confirmed occurrence of kozoite-(Nd) in the world is its type locality – the Tenno quarry, located in Matsushiro, Ehime Prefecture, on Shikoku Island, Japan.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of kozoite-(Nd) specimens is primarily assessed based on the abundance and size of aggregates on the rock matrix. Since the mineral is microscopic, specimens where the spherulitic aggregates are numerous, well-formed, and visible under low magnification are most valued. Contrast with the matrix (e.g., dark aegirine) and the presence of rare associated minerals are also important. ## Popular Localities The only source of specimens is the Tenno quarry in Japan. Material from this locality is extremely difficult to obtain and appears on the collector's market sporadically.

Care and storage

## Cleaning Due to the extreme delicacy and microscopic size of the aggregates, mechanical cleaning is not recommended and can lead to the destruction of the specimen. If it is necessary to remove loose dust, compressed air can be used from a safe distance. ## What to Avoid Contact with acids, which rapidly decompose carbonates, should be strictly avoided. Avoid ultrasonics, steam cleaners, and all chemical agents. Protect from high temperatures, which can cause thermal decomposition of the mineral. ## Storage Kozoite-(Nd) specimens are usually very small and fragile, so they should be stored in stable conditions, in sealed "micromount" boxes, to protect them from mechanical damage, dust, and sudden changes in humidity.

Sources

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