Nchwaningite

Chemical formula: Mn<sup>2+</sup><sub>2</sub>SiO<sub>3</sub>(OH)<sub>2</sub>·H<sub>2</sub>O

A rare, hydrated manganese silicate with a characteristic pinkish-red color, forming acicular or radial aggregates.

## Characteristics Nchwaningite is a rare, hydrated manganese silicate that typically occurs as small, acicular crystals. These crystals often form radial or chaotically arranged aggregates, resembling felt. Its most characteristic feature is its intense, pinkish-red color, which makes it easily recognizable despite the small size of its crystals. ## Physical Properties This mineral has a hardness of approximately 3 on the Mohs scale. It has a vitreous luster and is transparent to translucent. Its density is about 3.11 g/cm³. ## Colors and Varieties Nchwaningite occurs in shades from pink to reddish-pink. No distinct color or commercial varieties are recognized. ## History and Name The mineral's name comes from its discovery locality – the N'chwaning mine in the Kalahari Manganese Field in the Republic of South Africa. It was described and approved as a new mineral species in 1995 by D. G. Ginter, D. L. Bish, and R. T. Downs.

Properties

Mohs hardness
3
Luster
Vitreous
Streak
White
Density
3.11
Cleavage
Good on {010}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Key diagnostic features of nchwaningite include its characteristic pinkish-red color, acicular crystal habit, and occurrence in radial aggregates. Its low hardness (around 3) is also helpful for identification. ## Distinguishing from Similar Minerals Nchwaningite is sometimes confused with rhodochrosite, which often co-occurs in the same localities. However, rhodochrosite is harder (3.5-4), has perfect rhombohedral cleavage, and typically forms crystals of a different shape (scalenohedra, rhombohedra) or massive aggregates. Other pink manganese silicates, such as rhodonite, are significantly harder (5.5-6.5). ## Crystal Forms Nchwaningite forms elongated, acicular or hair-like crystals, which almost always occur as radial, stellate, or haphazardly entangled aggregates. Single, well-formed crystals are extremely rare.

Geological environment

## Genesis Nchwaningite is a hydrothermal mineral. It forms at low temperatures in manganese deposits, crystallizing in fissures and rock cavities. Its formation is associated with the circulation of aqueous solutions within manganese-rich sedimentary rocks. ## Mineral Associations This mineral often co-occurs with other manganese minerals, such as rhodochrosite, kutnohorite, hematite, hausmannite, as well as calcite and barite. ## Localities The most important and type locality for nchwaningite is the N'chwaning I and N'chwaning II mines in the Kuruman area, within the Kalahari Manganese Field in the Northern Cape Province (RSA). This is practically the only locality from which specimens of this mineral originate.

Rarity

Very rare

For collectors

## Quality Criteria The most prized nchwaningite specimens are those that exhibit an intense, saturated pinkish-red color. Well-defined, radial aggregates ("hedgehog" or "sunburst" formations) set on a contrasting rock matrix, such as white calcite or dark hausmannite, are highly valued. The size of the aggregates and the absence of damage to the delicate needles are also important. ## Popular Localities The N'chwaning mines in South Africa are the sole source of collectible nchwaningite specimens. Specimens from this locality are considered classic and most desirable.

Care and storage

## Cleaning Nchwaningite specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its low hardness and delicate structure, washing in water, and especially using ultrasonic cleaners, should be avoided. ## What to Avoid Contact with acids and other chemicals that can damage the mineral should be avoided. It is sensitive to scratches and impacts. It should not be heated or exposed to prolonged strong sunlight. ## Storage It is recommended to store specimens in separate, padded collector's boxes to protect them from mechanical damage and dust. It is best to keep it away from harder minerals.

Sources

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