Manganoeudialyte

Chemical formula: Na<sub>14</sub>Ca<sub>6</sub>Mn<sup>2+</sup><sub>3</sub>Zr<sup>4+</sup><sub>3</sub>[Si<sub>26</sub>O<sub>72</sub>(OH)<sub>2</sub>](H<sub>2</sub>O,Cl,O,OH)<sub>6</sub>

A rare cyclosilicate from the eudialyte group, distinguished by its manganese dominance, which gives it a characteristic pink to purplish-red coloration.

## Characteristics Manganoeudialyte is a mineral belonging to the complex eudialyte group, characterized by a significant manganese content. Typical specimens form granular aggregates or poorly developed crystals within the host rock. Its color, ranging from pink through red to purplish-red, is its most recognizable visual feature. It rarely occurs as well-formed, transparent crystals, and most material is translucent to opaque. ## Physical Properties This mineral has a hardness ranging from 5-6 on the Mohs scale. It exhibits a vitreous luster, and on fracture surfaces, it can be dull or greasy. It is relatively brittle, and its fracture is uneven to conchoidal. The density is approximately 2.86 g/cm³. ## Colors and Varieties The dominant color is pink to red, often with a violet hue, which is directly related to the presence of manganese ions (Mn²⁺) in its crystal structure. No formal varieties are distinguished, and its name directly indicates its chemical composition. ## History and Name The name "manganoeudialyte" derives from its association with eudialyte and the dominance of manganese in its chemical composition. It was formally described as a new mineral species relatively recently, and its status was approved by the International Mineralogical Association (IMA). It represents the manganese analog of eudialyte. ## Uses Due to its rarity and typically small crystal sizes, manganoeudialyte has no industrial applications. However, it is a valued and sought-after collector's mineral, especially specimens with intense coloration and well-formed crystals.

Properties

Mohs hardness
5-6
Luster
Vitreous
Streak
White
Density
2.86
Cleavage
None
Fracture
Uneven to Conchoidal
Transparency
Transparent to Translucent
Crystal system
Trigonal

Diagnostic features

## Identification The key diagnostic feature is its intense, pinkish-red color combined with its specific occurrence environment (alkaline nepheline syenites). It occurs in association with other rare minerals, which is also an important clue. It reacts with acids. ## Distinguishing from Similar Minerals It can be confused with other minerals from the eudialyte group, especially eudialyte itself. Final distinction often requires chemical analysis to confirm the dominance of manganese over iron. Rhodonite and rhodochrosite have different physical properties (hardness, cleavage) and occur in different parageneses. ## Crystal Forms Most often, it forms embedded, granular, or massive aggregates. Less commonly, poorly developed, tabular or short prismatic crystals with a trigonal cross-section, usually of small size, are found.

Geological environment

## Genesis Manganoeudialyte is an igneous mineral, crystallizing in the late stages from highly differentiated, silica-undersaturated alkaline magmas. It forms in nepheline syenites and associated pegmatites. ## Mineral Associations It co-occurs with other minerals typical of alkaline rocks, such as nepheline, microcline, aegirine, arfvedsonite, lorenzenite, lamprophyllite, and also other minerals from the eudialyte group. ## Localities The most important and well-known locality, which is also the type locality, is the Khibiny Massif on the Kola Peninsula in Russia. This is the main source of the best specimens of this mineral worldwide. Occurrences have also been reported in the Ilímaussaq complex in Greenland and at Mont Saint-Hilaire in Quebec (Canada).

Rarity

Rare

For collectors

## Quality Criteria The most highly valued specimens are those with well-formed, sharp crystals of intense, purplish-red color and good transparency. Contrast with a light host rock (most often nepheline or microcline) and the presence of rare associated minerals are also important. Large, single crystals are exceptionally sought after. ## Popular Localities By far the most desired specimens by collectors come from the Khibiny Massif on the Kola Peninsula in Russia. Material from this locality sets the standard of quality for this mineral.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, a damp cloth with distilled water can be used, followed by immediate and thorough drying. Avoid ultrasonic cleaners, which can cause cracks. ## What to Avoid The mineral is sensitive to acids, which can damage it. Avoid sudden temperature changes and prolonged exposure to direct sunlight, which can cause the intense color to fade. Protect from moisture. ## Storage It is recommended to store specimens in a dry place, in separate, padded boxes to prevent scratching by harder minerals. It is best to display it in closed display cases, away from heat sources and direct light.

External references

Sources

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