Zanazziite

Chemical formula: Ca<sub>2</sub>Mg<sub>5</sub>Be<sub>4</sub>(PO<sub>4</sub>)<sub>6</sub>(OH)<sub>4</sub>·6H<sub>2</sub>O

Zanazziite is a rare mineral from the phosphate group, forming small, vitreous crystals with a characteristic apple-green color.

## Characteristics Zanazziite is a hydrated beryllium, calcium, and magnesium phosphate, belonging to the roscherite group. It occurs as very small, tabular or prismatic crystals, rarely exceeding 1-2 mm in length. Most often, it forms radial or rosette-like aggregates, growing on the surface of other minerals. Its crystals are characterized by an intense, vitreous luster. ## Physical Properties This mineral has a hardness of approximately 5 on the Mohs scale. It is relatively brittle. Its crystals are usually transparent to translucent. The density of zanazziite is about 2.75 g/cm³. ## Colors and Varieties Zanazziite occurs in shades of green – from light green, through apple-green, to greenish-yellow. Some specimens may exhibit weak pleochroism in shades of green and yellow. No commercial or color varieties are distinguished. ## History and Name The mineral's name, given in 1988, honors Pierfranco Zanazzi, an Italian crystallographer and professor at the University of Perugia, for his contributions to the study of the structure of minerals from the roscherite group. It was discovered and described based on material from the Córrego do Urucum pegmatite in Minas Gerais, Brazil. ## Applications Zanazziite has no industrial applications. Its significance is purely scientific and collectible, being a prized micromineral due to its rarity and aesthetic forms of occurrence.

Properties

Mohs hardness
5
Luster
Vitreous
Streak
White
Density
2.75
Cleavage
Good on {010}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Characteristic features of zanazziite include its apple-green color, vitreous luster, and typical forms of occurrence as radial or rosette-like aggregates of small, tabular crystals. It occurs almost exclusively in granitic pegmatites. ## Distinguishing from Similar Minerals Zanazziite can be confused with other minerals from the roscherite group, such as roscherite or greifensteinite. Definitive differentiation requires advanced analytical methods, such as spectroscopy or X-ray diffraction. Visually, it may resemble other secondary phosphates, e.g., wardite, but differs from them in crystal form and environment of occurrence. ## Crystal Forms Zanazziite crystals are most often tabular, flattened parallel to {010}, or short prismatic. They form characteristic fan-shaped, spherulitic, or rosette-like aggregates, embedded in the host rock or growing on other minerals.

Geological environment

## Genesis Zanazziite is a hydrothermal mineral, crystallizing in the late stages of the evolution of complex granitic pegmatites. It forms as a result of metasomatic alteration of primary phosphates, such as triplite, in the presence of beryllium-rich solutions. ## Mineral Associations This mineral co-occurs with other pegmatitic phosphates. Its most common associated minerals are eosphorite, wardite, brazilianite, apatite, hydroxylherderite, quartz, muscovite, and other minerals from the roscherite group. ## Localities The most important and classic locality for zanazziite is the Córrego do Urucum pegmatite in the Galiléia region, Minas Gerais state, Brazil, from which the type material originates. It is also known from several other pegmatites in the same state, e.g., from the Sapucaia mine. Outside Brazil, its occurrences have been reported in Pakistan.

Rarity

Very rare

For collectors

## Quality Criteria The most valued specimens by collectors are those with well-formed, sharp crystals forming aesthetic, radial aggregates. Intense, apple-green color and good contrast with the matrix mineral are highly appreciated. Due to the small size of the crystals, specimens are mainly evaluated under a microscope. ## Popular Localities By far the most sought-after and classic zanazziite specimens come from its type locality – Córrego do Urucum in Minas Gerais, Brazil. Material from this location is considered exemplary for the species.

Care and storage

## Cleaning Zanazziite specimens should be cleaned with the utmost care, using a soft brush to remove dust. Brief rinsing in distilled water is permissible, followed by thorough drying. Due to the small size of the crystals, mechanical or ultrasonic cleaning is excluded. ## What to Avoid Avoid contact with acids and other chemicals that can damage delicate crystals. The mineral is brittle, so it must be protected from impacts and vibrations. It should not be heated, as it may lose structural water. ## Storage Collections with zanazziite, most often in the form of microminerals, are best stored in specialized, sealed boxes (e.g., "micromount" type), which protect delicate crystals from dust and mechanical damage. Exposure to moisture should be avoided.

External references

Sources

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