Hydroxylbenyacarite
Chemical formula: (H<sub>2</sub>O)<sub>2</sub>Mn<sub>2</sub>(Ti<sub>2</sub>Fe)(PO<sub>4</sub>)<sub>4</sub>[O(OH)](H<sub>2</sub>O)<sub>10</sub>·4H<sub>2</sub>O
Hydroxylbenyacarit is an extremely rare, hydrated manganese, titanium, and iron phosphate, forming orange, radial crystal aggregates.
Description
## Characteristics Hydroxylbenyacarit is a complex, hydrated phosphate belonging to the benyacarit group. It occurs as small, radial or divergent aggregates composed of tiny, prismatic or acicular crystals. Individual crystals rarely exceed 0.5 mm in length. This mineral is characterized by a vivid orange or yellowish-orange color, which makes it visually recognizable despite its small size. ## Physical Properties It is a relatively soft mineral, with a Mohs hardness of 2.5. Its luster is described as vitreous. It is translucent, meaning light can pass through its thin edges. The mineral's density is approximately 2.45 g/cm³. ## Colors and Varieties This mineral occurs in uniform shades from yellowish-orange to orange. No color varieties or commercial names are known, which is typical for such rare mineral species. ## History and Name Hydroxylbenyacarit was recognized as a new mineral by the International Mineralogical Association (IMA) in 2005. Its name refers to two features: the dominance of the hydroxyl (OH) group in its chemical structure and its close relationship to the mineral benyacarit. Benyacarit, in turn, was named after María Angélica Benyacar (1928–2007), an Argentine chemist and physicist. ## Applications Due to its extreme rarity and occurrence in microscopic quantities, hydroxylbenyacarit has no industrial applications. It serves solely as an object of scientific research and is a valuable acquisition for specialized collectors of rare minerals.
Diagnostic features
## Identification Characteristic features of hydroxylbenyacarit include its orange color, vitreous luster, and typical occurrence in radial aggregates of small, acicular crystals. A key diagnostic clue is also its paragenesis – co-occurrence with other rare phosphates in a pegmatitic environment. ## Distinguishing from Similar Minerals Hydroxylbenyacarit can be confused with other secondary phosphates of similar appearance, such as strunzite or cacoxenite. Strunzite forms similar radial aggregates but usually has a straw-yellow or light-yellow color. Cacoxenite is most often golden-yellow to brownish. Certain distinction of these minerals under amateur conditions is practically impossible and requires advanced analytical methods, such as chemical composition analysis (EDS) or X-ray diffraction (XRD). ## Crystal Forms This mineral forms characteristic radial or divergent aggregates. These consist of elongated, prismatic to acicular crystals, which are too small to observe their details without magnification.
Geological environment
## Genesis Hydroxylbenyacarit is a secondary mineral, meaning it forms as a result of the alteration of pre-existing minerals. It forms in the oxidation zones of complex granitic pegmatites, through hydrothermal alteration of primary phosphates, such as triphylite. ## Mineral Associations This mineral occurs in association with other, often rare, phosphate minerals. Its most common associations include rockbridgeite, strunzite, triphylite, and wolfeite. The presence of these minerals is an important clue for identification. ## Localities Hydroxylbenyacarit is known from only one locality in the world – its type locality. It was discovered in the Gigante pegmatite, in the Candelaria district, Punilla department (Córdoba province) in Argentina.
Rarity
Extremely rare
Collector aspects
## Quality Criteria As an extremely rare mineral, every specimen of hydroxylbenyacarit is valuable to collectors specializing in systematic mineralogy. Samples with well-formed, rich radial aggregates of intense orange color are most highly prized. Important criteria also include contrast with the rock matrix and the size of the aggregates themselves, although they rarely exceed a few millimeters in diameter. ## Popular Localities The only source of hydroxylbenyacarit specimens is its type locality – the Gigante pegmatite in Argentina. All samples available worldwide originate from this single locality.
Care and storage
## Cleaning Hydroxylbenyacarit specimens are very delicate and soft, so they should be handled with the utmost care. For dust removal, it is best to use a soft brush or a photographic air blower. Wet cleaning should be avoided, especially with detergents or ultrasonic cleaners, which could irreversibly damage the fragile crystals. ## What to Avoid The mineral is sensitive to chemicals, especially acids. As a hydrated mineral, it can be damaged (dehydrated) by high temperatures or very low humidity conditions. Prolonged exposure to direct sunlight should also be avoided, as it could theoretically cause its color to fade. ## Storage It is recommended to store specimens in closed, padded "micromount" boxes or display cases to protect them from dust, mechanical damage, and sudden changes in humidity. Stable environmental conditions are crucial for preserving the integrity of this rare mineral.