Schuilingite-(Nd)

Chemical formula: Cu<sup>2+</sup>Pb<sup>2+</sup>Nd(CO<sub>3</sub>)<sub>3</sub>(OH)·1.5H<sub>2</sub>O

A rare hydrated lead, copper, and neodymium carbonate, forming characteristic blue rosette-like aggregates.

## Characteristics Schuilingite-(Nd) is a rare secondary mineral from the carbonate group. It occurs as small, bladed crystals up to 1 mm long, often forming spherical aggregates or rosettes. Its most characteristic visual feature is an intense, sky-blue or pale blue color, which distinguishes it in paragenesis with other minerals of the oxidation zone. ## Physical Properties This mineral is relatively soft, with a Mohs hardness ranging from 3-4. It is quite heavy, with a density of approximately 4.8 g/cm³. The luster is vitreous, and on cleavage planes, it can be pearly. It is a translucent mineral. ## Colors and Varieties Schuilingite-(Nd) occurs in shades of blue, from pale to intensely blue. The suffix -(Nd) indicates that neodymium is the dominant rare-earth element in its structure. Other varieties from this group exist, e.g., schuilingite-(Gd) with gadolinium, which are macroscopically indistinguishable. ## History and Name The mineral was first described in 1982 by Paul Piret and Michel Deliens. Its name honors Hendrik Johann Schuiling (1896-1983), a Dutch geologist. The suffix -(Nd) was added later to distinguish it from other members of the schuilingite group, according to the rules for naming minerals containing rare-earth elements. The type locality is the Kasompi mine in the Democratic Republic of Congo. ## Uses Due to its extreme rarity and occurrence as small crystals, schuilingite-(Nd) has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals and for scientific institutions.

Properties

Mohs hardness
3-4
Luster
Vitreous, Pearly
Streak
Pale blue
Density
4.83
Cleavage
Perfect on {100}
Transparency
Translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Key diagnostic features include its blue color, characteristic crystal habit (blades), and aggregate forms (rosettes, spherical aggregates). An important indicator is also its paragenesis – co-occurrence with other secondary copper, lead, and uranium minerals in oxidation zones. ## Differentiation from Similar Minerals Schuilingite-(Nd) can be confused with other blue secondary minerals, such as aurichalcite, spangolite, or rosasite. However, aurichalcite forms acicular or fibrous crystals, not bladed ones. Spangolite crystallizes in a different system and has a different habit. Definitive differentiation from other visually identical members of the schuilingite group (e.g., with gadolinium) is only possible using advanced analytical methods, such as energy-dispersive spectroscopy (EDS). ## Crystal Forms Crystals are thin, flattened, with a bladed habit. They usually occur in radial aggregates, forming striking rosettes or crusts composed of small, spherical aggregates.

Geological environment

## Genesis This is a secondary mineral, formed in the oxidation (weathering) zone of polymetallic deposits rich in copper and lead. The presence of rare-earth elements, such as neodymium, is associated with the simultaneous weathering of primary uranium minerals (e.g., uraninite), which often contain traces of these elements. ## Mineral Associations Schuilingite-(Nd) is often accompanied by other secondary minerals. In the type locality (Kasompi mine), its co-occurrence with malachite, cerussite, kasolite, becquerelite, curite, and native copper has been observed. ## Localities The most important and historically first occurrence, from which the best specimens originate, is the Kasompi mine in Katanga Province, Democratic Republic of Congo. It is a very rare mineral, reported in only a few places worldwide, but Kasompi remains a key locality for collectors.

Rarity

Very rare

For collectors

## Quality Criteria The most highly valued specimens are those with well-formed, sharp crystals forming complete, undamaged rosettes. The intensity and purity of the blue color significantly increase the value. The attractiveness is also enhanced by a contrasting substrate (rock matrix) and the presence of other well-formed rare associated minerals. Due to the small size of the crystals, specimens are primarily evaluated under a microscope. ## Popular Localities The only source of specimens of collector significance is the historical type locality – the Kasompi mine in the Democratic Republic of Congo. Specimens from this location are considered classic and most desirable.

Care and storage

## Cleaning Specimens should be cleaned very carefully, preferably using compressed air to remove dust. If wet cleaning is necessary, use only distilled water and a very soft brush, avoiding strong rubbing. After cleaning, the specimen should be thoroughly dried. ## What to Avoid As a carbonate, schuilingite-(Nd) is very sensitive to acids, which cause its rapid dissolution. Contact with any household chemicals should be avoided. The mineral is soft and brittle, so it must be protected from impacts and scratches. Ultrasonic cleaners or steam cleaning should not be used. Prolonged exposure to strong sunlight should also be avoided. ## Storage It is recommended to store specimens in closed, padded "micromount" boxes that protect them from dust, mechanical damage, and sudden changes in humidity. A label with the name and locality should be permanently assigned to the specimen.

Sources

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