Sclarite
Chemical formula: Zn²⁺₇(CO₃)₂(OH)₁₀
Sclarite is a rare, hydrated zinc carbonate, forming microscopic, colorless crystals and light gray, radial aggregates.
Properties
- Mohs hardness
- 3-4
- Luster
- Vitreous, Pearly
- Streak
- White
- Density
- 3.51
- Fracture
- Irregular/Uneven
- Transparency
- Transparent,Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Sclarite is difficult to identify visually without specialized equipment. It is recognized mainly by its characteristic mode of occurrence – small, radial aggregates of a light gray color, deposited on the typical Franklin deposit rock matrix. The locality and co-occurrence with other minerals from this paragenesis are crucial. Confirmation requires advanced analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other secondary, white or colorless zinc minerals, such as hydrozincite or smithsonite. Hydrozincite often forms coatings and efflorescences, and under UV radiation, it exhibits strong, blue fluorescence, which sclarite does not possess. Smithsonite is harder and often forms botryoidal or reniform aggregates with a pearly luster. ## Crystal Forms It forms microscopic, bladed or acicular crystals, elongated along one axis. These crystals combine into characteristic, radial or spherulitic (spherical) aggregates.
Geological environment
## Genesis Sclarite is a secondary hydrothermal mineral that formed as a result of the alteration of primary zinc ores in the Franklin deposit. It forms at low temperatures in fractures and voids within metamorphosed, stratiform zinc, iron, and manganese ore deposits. ## Mineral Associations This mineral occurs in association with other, often rare, minerals from the Franklin deposit. It most commonly co-occurs with franklinite, willemite, zincite, roepperite (a zinc- and manganese-rich variety of olivine), as well as calcite and other secondary zinc minerals. ## Localities The only confirmed and described occurrence of sclarite in the world is its type locality – the Franklin Mine in Sussex County, New Jersey, USA. This is one of the most mineralogically diverse places on Earth.
Rarity
Very rare
For collectors
## Quality Criteria The quality of a sclarite specimen primarily depends on the size and development of the radial aggregates. The most prized specimens are those where the spherulitic clusters are clearly visible, well-formed, and contrast with the rock matrix. Association with other rare minerals from Franklin is also important, as it enhances the scientific and aesthetic value of the specimen. Due to the microscopic nature of the crystals, clarity and transparency are not key criteria. ## Popular Localities The only source of sclarite specimens is the historic Franklin Mine in New Jersey, USA. All specimens available on the collector's market originate from this single location, which makes them particularly sought after by specialists collecting systematic minerals and minerals from this specific locality.
Care and storage
## Cleaning Sclarite specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its softness and potential reactivity as a carbonate, washing in water, especially tap water, should be avoided. If it is necessary to remove loose contaminants, compressed air can be used from a safe distance. ## What to Avoid Contact with acids (even weak ones, like vinegar) must be absolutely avoided, as they will cause rapid dissolution of the mineral. Avoid ultrasonic cleaners, hard brushes, and strong chemicals. The mineral is soft and brittle, making it very susceptible to mechanical damage. ## Storage Sclarite specimens, as microminerals, are best stored in closed, padded "micromount" boxes, which protect them from dust, shocks, and contact with other minerals. Exposure to humid environments should be avoided.