Phosphammite

Chemical formula: (N³⁻H₄)₂(PO₃OH)

Phosphammite is a very rare, naturally occurring ammonium hydrogen phosphate, found in bat guano deposits.

## Characteristics Phosphammite is a very rare mineral from the phosphate group. Chemically, it is ammonium hydrogen phosphate. It occurs as brittle, earthy or powdery aggregates, as well as small, poorly formed crystals. Its appearance is inconspicuous; it most often forms white or colorless coatings and crusts on rocks or in organic material. ## Physical Properties This mineral is extremely soft, with a Mohs hardness of only 1, meaning it can be scratched with a fingernail. It is also very light, with a density of approximately 1.62 g/cm³. Crystals, though rare, are usually translucent and exhibit an irregular or uneven fracture. ## Colors and Varieties Phosphammite is typically colorless to white. There are no distinct colored varieties or trade names, which is typical for such a rare and unstable mineral. ## History and Name The name "phosphammite" refers to its chemical composition – it contains phosphate (phosph-) and an ammonium group (-amm-). The mineral was first described in 1870. The type locality, from which the first described material originated, is Earles Find near Lake Rason in Western Australia. ## Uses Due to its extreme rarity, instability, and inconspicuous appearance, phosphammite has no industrial or commercial applications. It is solely an object of scientific interest and a collector's item for specialized collectors of rare minerals.

Properties

Mohs hardness
1
Streak
White
Density
1.62
Fracture
Irregular/Uneven
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Identifying phosphammite in the field is difficult due to its inconspicuous appearance and rarity. Key features include its occurrence in a specific environment (caves, guano deposits), extreme softness (Mohs hardness 1), and water solubility. Identification usually requires advanced analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other white, earthy, or powdery secondary minerals found in caves, such as calcite, gypsum, or other rare phosphates. Phosphammite differs from them primarily by its extreme softness and reaction to water. Gypsum is harder (2 on the Mohs scale), and calcite is significantly harder (3) and reacts with hydrochloric acid. ## Crystal Forms Phosphammite rarely forms well-developed crystals. It usually occurs as earthy, powdery aggregates, as well as crusts or small, tabular monoclinic crystals.

Geological environment

## Genesis Phosphammite is a mineral of organic origin. It forms as a result of the reaction of phosphoric acid, derived from the decomposition of guano (bird or bat droppings), with ammonia released during the putrefaction of organic matter. It is a typical secondary mineral forming in dry, cave climates or within guano deposits. ## Mineral Associations This mineral coexists with other phosphates and evaporite minerals formed in guano deposits. Its typical associations include archerite, biphosphammite, brushite, weddellite, and gypsum. ## Localities Phosphammite is a very rare mineral, known from only a few localities worldwide. Besides the type locality at Earles Find in Western Australia, its occurrence has been confirmed, among others, in caves on Reunion Island in the Indian Ocean and in some caves in South Africa.

Rarity

Very rare

For collectors

## Quality Criteria In the case of such a rare mineral as phosphammite, the main criterion of value is its documented occurrence on a rock matrix. Specimens with visible, even small crystals, are significantly more valuable than earthy coatings. The abundance of the mineral on the specimen (amount of material) and a well-documented locality also increase its collector's value. ## Popular Localities Due to its extreme rarity, there are no "popular" localities in a commercial sense. Any specimen from a confirmed locality, such as Earles Find in Australia or caves on Reunion Island, is considered significant and highly sought after by specialized collectors of rare minerals.

Care and storage

## Cleaning Phosphammite specimens should absolutely not be cleaned wet. The mineral is water-soluble. The only permissible method for removing dust is to very gently use a soft brush or blow with compressed air from a distance. ## What to Avoid Avoid contact with water and any liquids that will dissolve it. The mineral is very sensitive to moisture and should be stored in a dry environment. As a very soft mineral, it is susceptible to any mechanical damage, abrasions, and scratches. ## Storage Phosphammite requires storage under specialized conditions. It is best kept in a sealed, transparent box (perky box) away from sources of moisture. A good practice is to place a moisture absorber (e.g., silica gel) in the display case or container.

External references

Sources

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