Newberyite
Chemical formula: Mg(PO₃OH)(H₂O)₃
Newberyite is a hydrated magnesium hydrogen phosphate, forming colorless or white crystals, found mainly in caves with bat guano.
Properties
- Mohs hardness
- 3-3.5
- Color
- Light gray to white or colorless, pale brown
- Luster
- Vitreous
- Streak
- White
- Density
- 2.10
- Cleavage
- On {010}, perfect; on {001}, poor.
- Fracture
- Hackly
- Transparency
- Translucent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Newberyite can be identified by its characteristic tabular crystals, often forming radial aggregates or rosettes. Key features include low hardness (can be scratched by a copper coin), perfect cleavage in one direction, and a pearly luster on cleavage planes. Its origin – occurrence in guano caves – is also characteristic. ## Distinguishing from Similar Minerals Newberyite is sometimes confused with other phosphates found in guano, such as hannayite or struvite. Hannayite has a similar appearance but crystallizes in the triclinic system and has different optical properties. Struvite also forms similar crystals but has slightly different hardness and density. Accurate differentiation often requires chemical or crystallographic analysis. ## Crystal Forms Newberyite crystals are typically tabular, flattened parallel to the cleavage plane. They often occur as fan-shaped, radial, or spherulitic rosettes. Single, well-formed crystals are less common.
Geological environment
## Genesis Newberyite is a mineral of organic origin. It forms mainly as a result of the reaction of phosphate-rich solutions, derived from the decomposition of guano (bat or seabird droppings), with magnesium-rich minerals or directly with carbonate rocks (limestones, dolomites) that form the cave substrate. It can also crystallize in sediments at the bottom of drying lakes. ## Mineral Associations This mineral often co-occurs with other phosphates formed under similar conditions, such as hannayite, struvite, apatite, as well as gypsum, calcite, and aragonite. ## Localities The most important and classic locality, from which large and well-formed crystals originate, is Skipton Caves in Victoria, Australia. Other known localities include caves in the Transvaal region of South Africa, some caves on the Somali Peninsula, and Ascension Island in the Atlantic Ocean, where it occurs in seabird guano deposits.
Rarity
Not very common
For collectors
## Quality Criteria For collectors, specimens with large, well-formed, transparent crystals are most desirable. Aesthetic, radial aggregates and rosettes several centimeters in diameter are particularly prized, especially those from the classic Australian locality. Purity (lack of inclusions) and absence of mechanical damage significantly increase the specimen's value. ## Popular Localities Specimens from Skipton Caves in Australia are by far the most valued by collectors. They are considered exemplary for this mineral. Specimens from other localities are also interesting but rarely match the quality of Australian ones.
Care and storage
## Cleaning Newberyite specimens should be cleaned very carefully, using a soft brush to remove dust. Distilled water can be used, but prolonged soaking should be avoided, as the mineral is soluble in acids and slightly soluble in water. After wet cleaning, the specimen should be thoroughly dried immediately. ## What to Avoid Contact with acids, which quickly dissolve it, must be strictly avoided. The mineral is sensitive to high temperatures, which can lead to its dehydration and destruction of its structure. As a soft mineral, it is susceptible to scratches and mechanical damage. ## Storage Collectible newberyite specimens are best stored in closed, padded boxes or display cases to protect them from dust, mechanical damage, and sudden changes in humidity. Avoid exposure to high humidity or direct sunlight.