Qatranaite

Chemical formula: CaZn²⁺₂(OH)₆(H₂O)₂

Qatranaite is a very rare calcium zinc hydroxide, forming colorless, tabular crystals with a hexagonal outline.

## Characteristics Qatranaite is a hydrated calcium zinc hydroxide. This mineral forms very small, colorless, tabular crystals with a hexagonal outline, reaching up to 0.2 mm in size. These crystals occur as rosette-like or radial aggregates, as well as single flakes. Due to its extreme rarity and microscopic crystal size, it is a mineral of purely scientific and collector's interest. ## Physical Properties Qatranaite crystals are transparent and exhibit a white streak. The luster is described as vitreous to pearly, especially visible on cleavage surfaces. Hardness and density have not been precisely measured due to the small size of the samples; however, the density calculated based on the formula and unit cell parameters is 3.31 g/cm³. ## History and Name The mineral's name comes from its discovery locality – the Qatrana Formation in the Daba-Siwaqa area of central Jordan. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2012 (IMA2012-057). It was described by a team of mineralogists, including H.-J. Förster and G. Stiebar.

Properties

Mohs hardness
3.5
Luster
Vitreous to pearly
Streak
White
Density
2.598
Cleavage
Perfect on {0001}
Fracture
Irregular/Uneven
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of qatranaite is possible only through advanced analytical methods, such as Raman spectroscopy and X-ray diffraction (XRD). Visually, at the occurrence site, it can be suspected based on the presence of small, hexagonal, colorless flakes in a characteristic geological environment. ## Distinguishing from Similar Minerals It can be confused with other secondary zinc minerals of similar appearance, such as hydrozincite or other hydroxides. Definitive differentiation requires chemical analysis (EDS) to confirm the composition (presence of calcium and zinc) and structural analysis. ## Crystal Forms Qatranaite crystallizes in the form of thin, tabular crystals with a hexagonal outline. These crystals often form radial or rosette-like aggregates, growing on the surface of the host rock.

Geological environment

## Genesis Qatranaite is a secondary mineral, forming in the oxidation zone of sulfide deposits. It forms as a result of low-temperature hydrothermal processes occurring in sedimentary rocks (bituminous marls). Its crystallization is associated with the interaction of zinc-rich solutions with carbonate rocks. ## Mineral Associations This mineral co-occurs with other secondary zinc and calcium minerals. At the type locality, it was found in association with calcite, sphalerite, pyrite, marcasite, quartz, gypsum, and other rarer zinc minerals. ## Localities The only confirmed locality for qatranaite in the world is its type locality: the Daba-Siwaqa area in the Qatrana basin, central Jordan. This site is known for the occurrence of many rare secondary minerals.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" mineral, the quality of a specimen is primarily determined by the abundance and development of crystals visible under a microscope. Specimens with numerous, well-formed, sharp, and undamaged crystals forming aesthetic aggregates are most valued. The size of individual crystals, even if sub-millimeter, also increases the specimen's value. Contrast with the surrounding host rock is an additional asset. ## Popular Localities The only source of qatranaite specimens is its type locality in Jordan. All samples available on the collector's market come from this single location.

Care and storage

## Cleaning Due to their microscopic size and delicacy, qatranaite specimens should not be cleaned mechanically or chemically. Any attempts at cleaning may damage the delicate crystals. It is safest to leave the specimen in its untouched state. ## What to Avoid Avoid contact with any chemicals, including acids and bases. The mineral is likely sensitive to changes in temperature and humidity. It should not be subjected to ultrasonic cleaning. Protect it from dust and mechanical damage. ## Storage Qatranaite specimens, due to their size and fragility, should be stored exclusively in specialized, sealed "micromount" boxes. This protects them from dust, shocks, and accidental touching. Display should only occur under a microscope.

External references

Sources

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