Parascholzite
Chemical formula: CaZn²⁺₂(PO₄)₂(H₂O)₂
Parascholzite is a rare hydrated zinc and calcium phosphate, forming colorless or white crystals with a bladed or tabular habit.
Properties
- Mohs hardness
- 4
- Color
- Colourless to white
- Luster
- Vitreous
- Streak
- white
- Density
- 3.12
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Parascholzite can be identified by its characteristic bladed or tabular crystals, often forming radial aggregates. Its colorless or white color, vitreous luster, and occurrence in paragenesis with other zinc phosphates are key features. It is insoluble in water. ## Distinguishing from Similar Minerals The most difficult task is distinguishing it from scholzite, with which it is dimorphous. Visually, these minerals can be identical, and certain differentiation requires specialized tests, such as X-ray diffraction (XRD). It can also be confused with other white or colorless secondary minerals, such as hemimorphite or hydrozincite, but it differs from them in crystal form and hardness. ## Crystal Forms Parascholzite crystals are typically small, with a bladed or tabular habit, elongated along one axis. They often form fan-shaped, radial, or rosette-like clusters and aggregates.
Geological environment
## Genesis Parascholzite is a secondary phosphate mineral that forms in the oxidation zones of zinc deposits, especially those occurring in sedimentary rocks rich in phosphates (phosphorites). It forms as a result of the alteration of primary zinc minerals in the presence of phosphate-rich solutions. ## Mineral Associations This mineral often co-occurs with other secondary zinc minerals and phosphates. Its most common associations include: scholzite, tarbuttite, hydrozincite, hemimorphite, spencerite, hopeite, and salmoite. ## Localities The most important and classic locality for parascholzite, from which the best specimens originate, is the Reaphook Hill mine in the Flinders Ranges, South Australia. It is also known from the Broken Hill mine in Zambia (formerly Northern Rhodesia), where it co-occurs with hopeite and tarbuttite.
Rarity
Rare
For collectors
## Quality Criteria Most valued by collectors are specimens with well-formed, sharp, and transparent crystals, forming aesthetic, radial or fan-shaped aggregates. Crystal size is also important – the larger they are, the more valuable the specimen. A contrasting combination with matrix rock or other associated minerals enhances the specimen's attractiveness. ## Popular Localities Undoubtedly, the most sought-after and highly valued parascholzite specimens come from its type locality – the Reaphook Hill mine in South Australia. Specimens from this location are considered the global standard for this mineral.
Care and storage
## Cleaning Parascholzite specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, distilled water can be used, but prolonged soaking should be avoided. Always ensure the specimen is completely dry before returning it to the collection. ## What to Avoid Avoid contact with acids and other aggressive chemicals, which can damage the mineral. As a relatively soft mineral, it is susceptible to scratches, so it must be protected from contact with harder minerals. It should not be heated, as this can lead to the loss of water from its structure (dehydration). ## Storage It is recommended to store parascholzite specimens in separate, padded collector boxes to prevent mechanical damage and abrasions. It should be protected from dust and moisture.