Kingsgateite

Chemical formula: Zr⁴⁺Mo⁶⁺₂O₇(OH)₂·2H₂O

Kingsgateite is a very rare, secondary zirconium molybdate, forming colorless, tabular crystals with an adamantine luster.

## Characteristics Kingsgateite is a hydrated zirconium molybdate, occurring as very small, colorless, tabular crystals, which rarely exceed 0.2 mm. The crystals are transparent and exhibit a strong, adamantine luster. They typically form small, scattered groups or individual crystals on the surface of the host rock. ## Physical Properties The mineral is characterized by a Mohs hardness of approximately 3. It has perfect cleavage in one direction, which is visible on larger crystals. Its calculated density is 3.65 g/cm³. ## Colors and Varieties Kingsgateite is colorless. No colored varieties or trade names are known. ## History and Name The mineral was discovered in the Old 25 Pipe mine in Kingsgate, Gough County, New South Wales, Australia. Its name is derived from its type locality. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2019, and its description was published in 2020. The authors of the description are Peter Elliott and Anthony R. Kampf. ## Uses Due to its extreme rarity and microscopic crystal sizes, kingsgateite has no industrial applications. It is solely an object of scientific and collecting interest for specialists who collect rare minerals and microminerals.

Properties

Mohs hardness
3
Color
yellowish green to bluish grey
Luster
Adamantine
Streak
white
Density
3.74
Cleavage
Perfect on {010}
Fracture
Irregular/Uneven
Transparency
Transparent
Crystal system
Tetragonal

Diagnostic features

## Identification Kingsgateite is difficult to identify visually without specialized equipment. It is recognized by its characteristic form of thin, tabular crystals, very strong, adamantine luster, and co-occurrence with other secondary molybdenum minerals in a specific geological environment. Definitive identification requires advanced analytical methods, such as Raman spectroscopy or X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other colorless, secondary minerals with a strong luster, such as cerussite or wulfenite, but it differs from them in crystal form and paragenesis. Wulfenite typically forms square crystals and is much more common. Certain distinction is only possible through chemical analysis. ## Crystal Forms Crystals are thin, tabular, with a hexagonal or pseudohexagonal outline. They occur as single, isolated crystals or small, loose aggregates.

Geological environment

## Genesis Kingsgateite is a secondary mineral that forms in the oxidation zones of molybdenum deposits. It results from the weathering of primary molybdenum minerals (mainly molybdenite) and zirconium in the presence of water. At the type locality, it occurs in voids within quartz breccia pipes. ## Mineral Associations This mineral co-occurs with other secondary molybdates, such as wulfenite and powellite, as well as with molybdenite, native bismuth, bismuthinite, quartz, and muscovite. ## Localities The only confirmed occurrence of kingsgateite in the world is its type locality: Old 25 Pipe mine, Kingsgate, Gough County, New South Wales, Australia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of kingsgateite specimens is assessed based on the sharpness and size of the crystals, their transparency, and luster. Specimens with well-formed, isolated crystals that stand out clearly from the host rock are most highly valued. Due to the microscopic nature of the mineral, the aesthetics of the entire sample and the richness of the mineral association are also crucial. ## Popular Localities The only source of specimens is the historic Old 25 Pipe mine in Kingsgate, Australia. Material from this locality is extremely rare and sought after by collectors specializing in rare minerals and microminerals.

Care and storage

## Cleaning Kingsgateite specimens should be handled with the utmost care due to their small size and fragility. Cleaning is not recommended, but if absolutely necessary, compressed air can be used from a safe distance to remove loose dust particles. Avoid contact with water and any chemicals. ## What to Avoid Avoid ultrasonic cleaners, chemical agents, acids, as well as high temperatures and sudden thermal changes. The mineral is soft and brittle, so it should be protected from any impacts and abrasions. ## Storage It is recommended to store specimens in specialized "micromount" boxes, which protect them from mechanical damage, dust, and moisture. Exposure to strong light is not advisable, although there is no evidence of fading.

External references

Sources

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