Scholzite

Chemical formula: CaZn₂+₂(PO₄)₂·₂H₂O

Scholzite is a rare hydrated zinc and calcium phosphate, forming fan-shaped or radial aggregates of colorless, white, or yellowish crystals.

## Characteristics Scholzite is a hydrated zinc and calcium phosphate, valued by collectors for its unique crystal forms. It most commonly occurs as fan-shaped, radial, or spherulitic aggregates, which consist of elongated, often acicular crystals. Single, well-formed crystals are rare. Specimens typically have a delicate, fibrous structure and a vitreous or silky luster, which gives them an attractive appearance. ## Physical Properties This mineral is relatively soft, with a Mohs hardness of 3 to 3.5. It is also quite light, with a density of approximately 3.11 g/cm³. The crystals are brittle and exhibit perfect cleavage in one direction, making them susceptible to mechanical damage. It is usually transparent to translucent. ## Colors and Varieties Scholzite is most often colorless or white. It can also take on pale yellow, yellowish-brown, or grayish hues, depending on impurities and formation conditions. No named varieties are distinguished. ## History and Name The mineral was first described in 1949 by the German mineralogist Heinz Strunz. The name "scholzite" was given in honor of Adolf Scholz (1894-1950), a German chemist and mineral collector from Regensburg, who provided the first samples for study. These specimens came from the Hagendorf-Süd mine in Bavaria, Germany, which is its type locality. ## Uses Scholzite has no industrial significance. It is solely a mineral of scientific and collecting interest, sought after for its rarity and aesthetic forms of crystal aggregates.

Properties

Mohs hardness: 3-3.5
Luster: Vitreous, Silky
Streak: White
Density: 3.11
Cleavage: Perfect on {010}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Characteristic features of scholzite are its typical aggregates: fan-shaped, radial, or spherical (spherulitic), composed of thin, bladed or acicular crystals. Low hardness, silky or vitreous luster, and occurrence in the oxidation zones of zinc deposits are key indicators. It reacts with acids. ## Distinguishing from Similar Minerals Scholzite is sometimes confused with other secondary phosphate minerals, such as tarbuttite, hopeite, or hemimorphite. It is distinguished from tarbuttite by its crystal form (tarbuttite rarely forms elongated needles) and lower density. Hopeite has a similar composition but crystallizes in the orthorhombic system and often forms more compact, tabular crystals. Hemimorphite, although forming similar aggregates, is harder (hardness 5) and is a silicate, not a phosphate. ## Crystal Forms Scholzite crystals are elongated along one axis, forming bladed, acicular, or hair-like forms. They almost always occur as radial, fan-shaped, or spherulitic aggregates. Well-formed, single crystals are rare.

Geological environment

## Genesis Scholzite is a secondary phosphate mineral that forms in the oxidation zones of hydrothermal zinc ore deposits. It forms as a result of the reaction of phosphate-rich solutions (derived, for example, from the decomposition of primary phosphate, such as apatite) with zinc minerals, such as sphalerite. It can also crystallize in granitic pegmatites containing phosphates and zinc minerals. ## Mineral Associations This mineral often co-occurs with other secondary phosphates and zinc minerals. Its most common associations include: tarbuttite, hopeite, parascholzite, phosphophyllite, sphalerite, rockbridgeite, strengite, and apatite. ## Localities The most important and historical locality, from which classic specimens originate, is the Hagendorf-Süd mine in Bavaria, Germany. Other significant localities worldwide include the Reaphook Hill mine in South Australia, known for large and well-formed aggregates, and the Skorpion mine in Namibia. Occurrences have also been reported in Zambia (Kabwe mine) and the United States (Utah).

Rarity

Rare

For collectors

## Quality Criteria The most prized scholzite specimens are characterized by well-defined, fan-shaped or spherulitic aggregates with a distinct luster. The size of the aggregates is crucial – specimens several centimeters in diameter are already considered exceptional. Purity and lack of damage to the delicate crystals are also important. A contrasting rock matrix, on which the aggregates are deposited, significantly enhances the visual appeal and value of the specimen. ## Popular Localities The best specimens worldwide are considered to be those from the Reaphook Hill mine in Australia, which stand out for the size and perfection of their radial aggregates. Classic, though usually smaller, are specimens from the type locality in Hagendorf, Germany. In recent years, attractive specimens from the Skorpion mine in Namibia have also appeared on the market.

Care and storage

## Cleaning Scholzite specimens should be cleaned with utmost care due to their brittleness and softness. It is best to use compressed air to remove dust. If wet cleaning is necessary, a soft brush and distilled water can be used, avoiding strong friction. After cleaning, the specimen should be dried immediately and thoroughly. ## What to Avoid Scholzite is sensitive to acids, which can damage or completely dissolve it. Contact with any household and laboratory chemicals should be avoided. The mineral is brittle, so it must be protected from impacts, falls, and vibrations. It should not be cleaned in ultrasonic cleaners. ## Storage Collectible scholzite specimens are best stored in separate, padded boxes to prevent abrasion and damage to the delicate crystals. They should be kept in stable conditions, away from sources of moisture and extreme temperatures. During display, they should be protected from dust and mechanical damage, for example, in a locked display case.

Sources

IMA Mineral List (CNMNC)