Hylbrownite

Chemical formula: Na₃MgP₃O₁₀·₁₂H₂O

Hylbrownite is a rare, hydrated sodium and magnesium phosphate, forming colorless, tabular crystals.

## Characteristics Hylbrownite is a rare, hydrated sodium magnesium triphosphate. It occurs as very small, colorless to white tabular crystals, reaching sizes up to 0.2 mm. The crystals are transparent and exhibit a vitreous luster. Due to its chemical composition and small size, it is a mineral of interest mainly to specialized collectors and scientists. ## Physical Properties This mineral is characterized by low hardness and a density of 1.81 g/cm³. It is transparent, with a white streak and vitreous luster. It exhibits cleavage in two directions, and its fracture is uneven. ## History and Name The mineral's name honors Hywel Vincent Brown (born 1960), an Australian mineral collector who discovered the first specimens of this mineral. Hylbrownite was approved as a new mineral species by the International Mineralogical Association (IMA) in 2010 (IMA2010-022).

Properties

Luster: Vitreous
Streak: White
Density: 1.81
Cleavage: parallel to {001} and to {100}
Fracture: Irregular/Uneven
Transparency: Transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of hylbrownite under amateur conditions is practically impossible. It requires advanced analytical techniques, such as X-ray diffraction (XRD) and Raman spectroscopy, due to its small size and occurrence in association with other rare phosphates. ## Distinguishing from similar minerals It can be confused with other colorless, secondary phosphate minerals found in the same locality, such as kanonerovite or nastrophite. Definitive distinction is only possible using specialized research methods. ## Crystal forms It forms very small, tabular crystals, often grouped into small aggregates.

Geological environment

## Genesis It is a secondary mineral, forming in the oxidation zones of copper deposits. In its type locality, it was found in cavities within dolomitic marble. ## Mineral associations It co-occurs with other rare minerals, such as kanonerovite, nastrophite, schertelite, struvite, and swaknoite. ## Localities The only confirmed occurrence of hylbrownite in the world is its type locality – the Dome Rock copper mine, located within the Boolcoomatta Reserve in South Australia.

Rarity

Extremely rare

For collectors

## Quality criteria As a "micromount" mineral, the quality of a specimen is primarily determined by the certainty of identification and the presence of well-formed, albeit microscopic, crystals on the rock matrix. Due to its extreme rarity, every confirmed specimen is scientifically and collectionally valuable.

Care and storage

## Cleaning Due to its extreme rarity and delicacy, specimens should not be cleaned mechanically or chemically. Any contaminants are best left undisturbed. ## What to avoid Avoid contact with water, chemicals, and temperature changes, which can cause dehydration and destruction of the mineral. The crystals are very brittle and susceptible to mechanical damage. ## Storage Hylbrownite specimens must be stored under stable conditions, preferably in a sealed, padded "micromount" box, protecting them from moisture, dust, and physical damage.

External references

https://www.mindat.org/min-41135.html