Reinhardbraunsite

Chemical formula: Ca₅(SiO₄)₂(OH)₂

Reinhardbraunite is a rare calcium silicate with a characteristic pale pink color, occurring as small, tabular crystals.

## Characteristics Reinhardbraunite is a hydrated calcium silicate belonging to the chegemite group. It forms very small, tabular or bladed crystals, rarely exceeding 1 mm in length, which often occur in radial or tangled aggregates. Its most characteristic visual feature is a delicate, pale pink color. ## Physical Properties This mineral has a hardness in the range of 5-6 on the Mohs scale. It has a vitreous luster and is translucent. Its density is approximately 2.85 g/cm³. It exhibits unidirectional cleavage, and its fracture is conchoidal. ## Colors and Varieties Reinhardbraunite occurs almost exclusively in pale pink shades. No color or commercial varieties are distinguished. ## History and Name The mineral was discovered and described in 1980. Its name honors Reinhard Brauns (1861-1937), a German mineralogist and professor at the University of Bonn, for his contribution to the study of mineralogy in the Eifel region, where this mineral was first found. ## Uses Reinhardbraunite has no industrial application. It is solely a mineral of scientific and collecting interest, sought after due to its rarity.

Properties

Mohs hardness
5-6
Luster
Vitreous
Streak
White
Density
2.85
Cleavage
On {001}
Fracture
Conchoidal
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Reinhardbraunite can be identified by its characteristic pale pink color, small, tabular crystals forming aggregates, and occurrence in a specific geological environment – within calc-silicate xenoliths in volcanic rocks. ## Distinguishing from Similar Minerals It can be confused with other rare minerals from the chegemite group or other pink silicates occurring in similar conditions, such as some zeolites. Certain identification requires advanced analytical methods, such as X-ray diffraction (XRD), due to the small crystal size and similarity to other minerals. ## Crystal Forms Crystals are typically very small, with a tabular or bladed habit. They most often form radial, stellate, or haphazardly tangled aggregates in fissures and small rock cavities.

Geological environment

## Genesis Reinhardbraunite forms under conditions of contact metamorphism. It develops in calc-silicate xenoliths that have been thermally altered by contact with magma in a volcanic environment. ## Mineral Associations This mineral co-occurs with other minerals typical of calc-silicate rocks, such as calcite, larnite, brownmillerite, mayenite, ettringite, and jennite. ## Localities The most important and type locality for reinhardbraunite is the Caspar quarry in Ettringen, in the Eifel region of Germany. This is the locality from which most known specimens originate. Beyond Germany, its presence has also been reported in Jebel Harmun in Palestine and in the Hatrurim region of Israel.

Rarity

Very rare

For collectors

## Quality Criteria The collecting appeal of a specimen depends on the size and development of the crystals and the intensity of the pink color. Specimens with clearly visible, radial aggregates on a contrasting matrix are most valued. Due to the microscopic nature of the mineral, the quality of the entire mineral assemblage is crucial. ## Popular Localities Undoubtedly, the most known and valued source of reinhardbraunite specimens is its type locality – the Caspar quarry in Ettringen, Germany. Specimens from this location are the standard for this mineral in collections worldwide.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using a soft brush to remove dust. Due to the small size of the crystals and their fragility, wet cleaning, especially with ultrasonic cleaners, is not recommended. ## What to Avoid Avoid contact with acids and other chemicals that may damage the mineral. The crystals are fragile and sensitive to impact and scratches. There is no detailed data on its sensitivity to light or temperature, but standard caution is advised. ## Storage The safest way to store specimens is to place them in a closed display box, which protects them from dust and mechanical damage. Due to the small size of the crystals, magnification (loupe, microscope) is necessary for their observation.

External references

Sources

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