Manganvesuvianite

Chemical formula: Ca<sub>19</sub>Mn<sup>3+</sup>Al<sub>10</sub>Mg<sub>2</sub>(SiO<sub>4</sub>)<sub>10</sub>(Si<sub>2</sub>O<sub>7</sub>)<sub>4</sub>O(OH)<sub>9</sub>

Manganvesuvianite is a manganese variety of vesuvianite, distinguished by its intense, reddish-purple color and occurrence in well-formed crystals.

## Characteristics Manganvesuvianite is a mineral from the sorosilicate group, belonging to the vesuvianite group. It is the manganese (Mn³⁺) analog of vesuvianite. It forms prismatic, columnar crystals with a square cross-section, terminated by pyramids. Crystals are often well-formed and can reach several centimeters in length. It also occurs in granular aggregates and radial clusters. Its most characteristic feature is an intense, deep reddish-purple to purplish color. ## Physical Properties This mineral is characterized by a hardness of approximately 6.5 on the Mohs scale. It has a vitreous luster, and its crystals are usually translucent, rarely transparent. The density is about 3.43 g/cm³. It does not exhibit fluorescence under ultraviolet light. ## Colors and Varieties The dominant and defining color of manganvesuvianite is reddish-purple, purple, or violet-red. The intensity and hue depend on the content of trivalent manganese in the crystal structure. No distinct commercial or color varieties are distinguished beyond its typical color range. ## History and Name The mineral's name, introduced in 1984 by William Panczner, directly refers to its chemical composition – the dominance of manganese – and its structural relationship with vesuvianite. It was first described in detail based on specimens from mines in the Kuruman Hills region of South Africa. ## Applications Due to its rarity, attractive color, and well-formed crystals, manganvesuvianite is a prized collector's stone. The best specimens, especially transparent ones, are sometimes cut and used as gemstones, although their use in this field is limited due to the small availability of material.

Properties

Mohs hardness
6.5
Luster
Vitreous
Streak
Light brown
Density
3.43
Cleavage
Poor on {001} and {110}
Fracture
Uneven to conchoidal
Transparency
Transparent to translucent
Crystal system
Tetragonal

Diagnostic features

## Identification Key diagnostic features of manganvesuvianite are its characteristic reddish-purple color, tetragonal crystal form (prismatic columns with a square cross-section), and vitreous luster. Hardness (approximately 6.5) is also helpful in identification. Occurrence in manganese skarns is an important field indicator. ## Distinguishing from Similar Minerals It can be confused with other purple minerals. From amethyst (a variety of quartz), it is distinguished by its crystal form (tetragonal, not trigonal) and higher hardness. From sugilite, it is most often distinguished by better crystal development and higher transparency. Other manganese minerals, such as rhodonite or rhodochrosite, usually have different hues (pink to red), lower hardness, and crystallize in different systems. ## Crystal Forms It crystallizes in the tetragonal system. It most often forms simple, elongated prismatic crystals with a square cross-section, often terminated by pyramid faces. Crystals can occur individually or form radial and granular aggregates.

Geological environment

## Genesis Manganvesuvianite is a mineral typical of metamorphosed manganese deposits, especially skarns and rodingites. It forms under conditions of relatively high temperatures and pressures as a result of metasomatism of rocks rich in calcium and silica, with the simultaneous presence of manganese. ## Mineral Associations It often co-occurs with other manganese minerals and calcium silicates. Its typical associated minerals include: calcite, hausmannite, braunite, andradite, diopside, as well as other minerals from the vesuvianite and garnet groups. ## Localities The most important and well-known localities worldwide, from which the best manganvesuvianite specimens originate, are in South Africa, in the Kuruman region of the Kalahari Desert. These are primarily the Wessels and N'Chwaning mines. This mineral has also been found in the Jeffrey Mine in Canada (Quebec) and in several localities in Italy.

Rarity

Rare

For collectors

## Quality Criteria The most highly valued manganvesuvianite specimens are those with a deep, saturated, reddish-purple color. Good crystal development is also key – sharp, undamaged, prismatic forms with a vitreous luster are sought after. High transparency and clarity (lack of inclusions) significantly increase value. Aesthetic compositions with associated minerals, such as white calcite, are also attractive. ## Popular Localities By far the most desired specimens by collectors come from the Wessels and N'Chwaning mines in South Africa. Crystals from these localities are considered exemplary in terms of color, form, and size.

Care and storage

## Cleaning Manganvesuvianite specimens should be cleaned gently, using a soft brush and lukewarm water, possibly with a small amount of mild soap. After washing, rinse thoroughly with clean water (preferably distilled) and allow to air dry completely or pat dry with a soft cloth. ## What to Avoid Avoid contact of the mineral with strong acids and chemicals, which can damage its surface. Do not clean it in ultrasonic or steam cleaners. Despite its relatively high hardness, it is brittle and sensitive to impact. Prolonged exposure to intense sunlight can potentially cause color fading, so it is advisable to avoid it. ## Storage Collector's specimens of manganvesuvianite are best stored in separate, padded boxes or display cases to prevent scratching by harder minerals (e.g., quartz, beryl) and to protect them from dust. It is worth protecting them from sudden temperature changes and direct sunlight.

External references

Sources

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