Gysinite-(Nd)

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

Gysinite-(Nd) is a rare mineral from the ancylite group, being a hydrated lead and neodymium hydroxycarbonate, forming tiny, pink crystals.

## Characteristics Gysinite-(Nd) is a rare mineral belonging to the ancylite group. Chemically, it is a hydrated lead and neodymium hydroxycarbonate. It occurs as very small, tabular or prismatic crystals, rarely exceeding 0.2 mm in length. These crystals often form rosette-like or spherulitic aggregates. Due to its size, it is a mineral mainly available to specialized collectors (so-called micromounters). ## Physical Properties Gysinite-(Nd) crystals exhibit a vitreous luster. Its hardness on the Mohs scale ranges from 4 to 4.5, and its density is approximately 4.83 g/cm³. It is a relatively brittle mineral. ## Colors and Varieties This mineral is characterized by a color ranging from pale pink to pinkish-violet. No color varieties or commercial forms are known. ## History and Name The name "gysinite" was given in honor of Marcel Gysin (1891-1974), professor of mineralogy and petrography at the University of Geneva, Switzerland. The suffix "-(Nd)" indicates the dominant rare earth element in its composition - neodymium. The mineral was first described in 1983 by Halil Sarp and Jacques Deferne based on material from the Shinkolobwe mine in the Democratic Republic of Congo.

Properties

Mohs hardness
4-4.5
Luster
Vitreous
Streak
White
Density
4.83
Cleavage
Good on {010}
Fracture
Uneven
Transparency
Translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Identification of gysinite-(Nd) is possible almost exclusively using advanced laboratory methods, such as X-ray diffraction (XRD) or chemical analysis (EDS/WDS). In collector conditions, identification is based on the morphological analysis of tiny, pink crystals in association with other secondary minerals from the oxidation zones of uranium deposits. ## Differentiation from Similar Minerals It can be confused with other minerals from the ancylite group or other secondary rare earth carbonates. Differentiation from ancylite-(Ce), ancylite-(La), or kamphaugite-(Y) requires specialized chemical analysis to determine the dominant rare earth element. ## Crystal Forms It forms very small, tabular crystals with a hexagonal outline or short prismatic crystals. It is most commonly found in the form of rosette-like or spherulitic (spherical) aggregates, growing on other minerals.

Geological environment

## Genesis Gysinite-(Nd) is a secondary mineral, forming in the oxidation (weathering) zones of hydrothermal ore deposits, especially those rich in uranium, lead, and rare earth elements. It forms as a result of the action of carbonate-rich waters on primary minerals containing neodymium and lead. ## Mineral Associations It co-occurs with other secondary minerals such as uraninite, schoepite, uranophane, kasolite, bijvoetite-(Y), kamotoite-(Y), schuilingite-(Nd), and quartz. ## Localities The most important occurrences of this mineral are its type locality - the Shinkolobwe mine in Katanga Province (Democratic Republic of Congo) and the Krunkelbach uranium mine (Menzenschwand) in the Black Forest (Germany).

Rarity

Very rare

For collectors

## Quality Criteria For micromineral collectors, specimens with well-formed, sharp crystals forming aesthetic, rosette-like aggregates are most desirable. The intensity of the pink color and the contrast with the host rock (matrix) also increase the value of the specimen. Due to their small size, the quality of the crystals visible under a microscope is crucial. ## Popular Localities Specimens from the type locality, the Shinkolobwe mine in DR Congo, are historically the most important. Currently, specimens from Menzenschwand in Germany also appear on the collector's market.

Care and storage

## Cleaning Due to the extreme brittleness and small size of the crystals, mechanical cleaning is not recommended. If absolutely necessary, compressed air can be used from a safe distance to remove dust. Avoid contact with water and any chemicals. ## What to Avoid As a carbonate, gysinite-(Nd) is sensitive to acids. It should be protected from moisture, sudden temperature changes, and direct sunlight, which can cause its color to fade. Avoid ultrasonic cleaners. ## Storage Specimens of gysinite-(Nd) should be stored under stable conditions, preferably in specialized micromount boxes, which protect them from mechanical damage, dust, and moisture.

Sources

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