Garyansellite

Chemical formula: Mg<sub>2</sub>Fe<sup>3+</sup>(PO<sub>4</sub>)<sub>2</sub>(OH)·2H<sub>2</sub>O

Garyansellite is a rare phosphate mineral, forming microscopic, tabular, brown crystals, found in guano deposits.

## Characteristics Garyansellite is a hydrated magnesium iron phosphate. It occurs as very small, tabular or bladed crystals, rarely exceeding 0.3 mm in length. These crystals form rosette-like or radial aggregates, as well as thin coatings and earthy masses. Due to the small size of the crystals, its visual features are difficult to observe without magnification. ## Physical Properties This mineral is characterized by a Mohs hardness of 4. It has a luster described as vitreous to dull, depending on its form of occurrence. It is translucent. Its calculated density is approximately 2.99 g/cm³. ## Colors and Varieties Garyansellite has a characteristic reddish-brown color. No varieties have been distinguished. ## History and Name The mineral is named in honor of Gary R. Ansell (born 1945), an American mineralogist and curator of the mineralogical collection at Harvard University, who first noticed this mineral. It was described and approved as a new mineral species in 1984. ## Uses Garyansellite has no industrial application. It is solely an object of interest for collectors specializing in rare minerals or micromounts.

Properties

Mohs hardness
4
Luster
Vitreous to dull
Streak
Light brown
Density
2.99
Cleavage
Good on {010}
Fracture
Uneven
Transparency
Translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Amateur identification of garyansellite is practically impossible due to the microscopic size of its crystals. Recognition requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). A preliminary indication may be its reddish-brown color, tabular crystal habit visible under a microscope, and its specific environment of occurrence (guano deposits). ## Distinguishing from Similar Minerals It can be confused with other fine-grained phosphates found in guano deposits, such as tinticite or leucophosphite. Differentiation without specialized equipment is impossible. ## Crystal Forms Garyansellite forms very small, thin, tabular crystals with a hexagonal or rhombic outline. These crystals often combine into radial or rosette-like aggregates, and also form earthy masses and crusts.

Geological environment

## Genesis Garyansellite is a secondary mineral, formed by the reaction of solutions derived from the decomposition of guano (bird droppings) with magnesium-rich rocks. It forms in dry, cave environments. ## Mineral Associations This mineral co-occurs with other phosphates typical of guano deposits, such as tinticite, leucophosphite, newberyite, collinsite, hannayite, and struvite. ## Localities The most important and best-documented garyansellite localities worldwide include: * **Western Australia:** Petrogale Cave and Wooltana Cave on the Nullarbor Plain (type locality). * **Namibia:** Arnhem Cave, southeast of Windhoek.

Rarity

Very rare

For collectors

## Quality Criteria For micromount collectors, the most valuable specimens are those with well-formed, sharp crystals forming aesthetic, rosette-like aggregates. Contrast with the matrix and the presence of associated minerals are also important. Due to its microscopic nature, the purity and size of individual crystals are less significant than the quality of the entire aggregate. ## Popular Localities The most prized specimens come from the type locality in Western Australia, especially from Petrogale Cave.

Care and storage

## Cleaning Garyansellite specimens are usually very small and fragile. They should be cleaned with the utmost care, using compressed air to remove dust. Any contact with water or a brush can damage the delicate aggregates. ## What to Avoid Avoid contact with water, chemicals, and especially acids, which can damage it. Protect it from vibrations and impacts. ## Storage It is recommended to store specimens in specialized micromount boxes, which protect them from dust, humidity, and mechanical damage. Display should be away from sources of vibration.

Sources

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