Pittongite
Chemical formula: (Na,H<sub>2</sub>O)<sub>0.7</sub>(W<sup>6+</sup>,Fe<sup>3+</sup>)(O,OH)<sub>3</sub>
A very rare, amorphous oxide of tungsten, sodium, and iron, forming earthy pseudomorphs after ferberite.
Description
## Characteristics Pittongite is an amorphous mineral, meaning it does not form crystals. It occurs as earthy, porous, and brittle aggregates or as pseudomorphs, which are secondary aggregates retaining the external form of the ferberite crystals they replaced. Its structure is very delicate, and the material crumbles easily. ## Physical Properties This mineral is characterized by very low hardness, approximately 1 on the Mohs scale, which means it is extremely soft. The luster is dull or earthy. Pittongite is opaque. Its density has not been measured, only calculated to be approximately 4.75 g/cm³. ## Colors and Varieties It ranges in color from yellowish-brown to reddish-brown. Due to its nature and rarity, no color or commercial varieties are distinguished. ## History and Name The name pittongite comes from its type locality – the Pittong kaolin quarry in Pittong, Victoria, Australia. The mineral was officially approved by the International Mineralogical Association (IMA) in 2018 (IMA2018-163), and its first scientific description was published in 2019. ## Applications Pittongite has no industrial applications. Its significance is purely scientific and it is an object of interest for specialized collectors of rare minerals.
Diagnostic features
## Identification Features allowing for preliminary identification of pittongite include its earthy appearance, very low hardness, yellowish-brown color, and occurrence as pseudomorphs after ferberite crystals. It often retains the hexagonal or tabular outline of the original mineral. Definitive identification is possible only through advanced analytical methods, such as X-ray diffraction (XRD) to confirm its amorphous nature and chemical analysis (EDS/WDS) to determine its composition. ## Distinguishing from Similar Minerals Pittongite can be confused with other secondary, earthy minerals, such as limonite (a mixture of iron oxides) or other rare "tungsten ochres" (e.g., tungstite). A key indicator is its genesis as a product of ferberite alteration. Final differentiation from similar rare tungsten oxides requires laboratory analysis. ## Crystal Forms Pittongite is an amorphous mineral and does not form its own crystals. It occurs exclusively as earthy aggregates and pseudomorphs after ferberite crystals, often retaining their original tabular or prismatic shape.
Geological environment
## Genesis Pittongite is a secondary mineral. It forms as a result of low-temperature hydrothermal processes or weathering, which lead to the alteration of primary tungsten minerals. In its type locality, it formed in the oxidation zone of quartz veins due to the alteration of ferberite. ## Mineral Associations This mineral occurs in direct proximity to the parent mineral from which it formed – ferberite. It is also associated with quartz and kaolinite, which is the main component of the surrounding rock. ## Localities The only confirmed locality of pittongite in the world is its type locality – the Pittong kaolin quarry in Pittong, Grenville County, Victoria, Australia.
Rarity
Extremely rare
Collector aspects
## Quality Criteria The collector's value of pittongite is solely related to its rarity and scientific significance. The most desirable specimens are distinct and complete pseudomorphs that clearly reflect the shape of the original ferberite crystals. An additional advantage is the presence of relics of unaltered ferberite or a clear association with quartz on the specimen. The size of the aggregate is also important, although most material occurs as small aggregates. ## Popular Localities As this mineral is known from only one location in the world, all available specimens come from the Pittong kaolin quarry in Australia. It is an extremely difficult mineral to acquire, found mainly in institutional collections and among specialized collectors of systematic minerals.
Care and storage
## Cleaning Due to its extreme softness (hardness ~1) and porous, earthy structure, pittongite is extremely susceptible to mechanical damage. It should not be cleaned mechanically, not even with a soft brush. The only safe method for removing dust is a gentle blast of compressed air from a distance. ## What to Avoid Contact with water and any chemicals that could penetrate its porous structure and cause it to disintegrate must be absolutely avoided. Ultrasonic cleaners are forbidden. The mineral should be protected from vibrations, impacts, and abrasion. ## Storage Pittongite specimens should be stored in a stable, dry environment. It is best to place them in a sealed "micromount" box, which will protect them from dust, moisture, and physical damage.