Phosphogartrellite

Chemical formula: Pb<sup>2+</sup>Cu<sup>2+</sup>Fe<sup>3+</sup>(PO<sub>4</sub>)<sub>2</sub>(OH,H<sub>2</sub>O)<sub>2</sub>

Phosphogartrellite is a rare secondary mineral of the tsumcorite group, being a hydrated lead, copper, and iron phosphate, forming small, tabular crystals.

## Characteristics Phosphogartrellite is a rare secondary mineral belonging to the tsumcorite group. Chemically, it is a hydrated lead, copper, and iron phosphate. It occurs as very small, tabular or bladed crystals, rarely exceeding 0.2 mm in length. These crystals often form rosette-like or radial aggregates, as well as thin coatings and crusts on rock surfaces. ## Physical Properties Phosphogartrellite crystals exhibit a vitreous luster. They are transparent to translucent. Due to the small size of the crystals, hardness and density have not been precisely measured, but only calculated based on chemical composition and unit cell parameters. The calculated density is approximately 4.45 g/cm³. ## Colors and Varieties This mineral is characterized by a yellowish-green to green color. No varieties have been distinguished. ## History and Name Phosphogartrellite was first described in 1998 by Werner Krause, Klaus Belendorff, Heinz-Jürgen Bernahrdt, Catherine McCammon, Herta Effenberger, and Werner Mikenda. Its name refers to its chemical composition – it is a phosphatic (Phospho) analogue of gartrellite, which is an arsenate. The name gartrellite, in turn, honors the Australian mineral collector, Benjamin Gartrell.

Properties

Luster
Vitreous
Streak
Light green
Density
4.45
Cleavage
Good on {001}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Triclinic

Diagnostic features

## Identification Identification of phosphogartrellite under amateur conditions is practically impossible and requires advanced analytical methods, such as Raman spectroscopy or chemical analysis (EDS/WDS). Preliminary identification is based on its characteristic form (small, tabular crystals in rosette-like aggregates), greenish color, and co-occurrence with other secondary minerals of the oxidation zone. ## Distinguishing from Similar Minerals Phosphogartrellite is visually indistinguishable from gartrellite, tsumcorite, and other rare phosphates and arsenates of this group. Certain differentiation is possible only based on chemical composition analysis, which allows determining the dominance of phosphorus over arsenic. ## Crystal Forms The crystals are very small, thin, and tabular, often with a hexagonal or rhombic outline. They typically form radial or rosette-like aggregates, as well as thin coatings on the host rock.

Geological environment

## Genesis Phosphogartrellite is a secondary mineral, forming in the oxidation zones (gossans) of polymetallic deposits rich in lead, copper, and iron. It forms as a result of the weathering of primary ore minerals (mainly galena, chalcopyrite) in the presence of phosphate-rich solutions. ## Mineral Associations This mineral co-occurs with other secondary minerals, such as segnitite, beudantite, hidalgoite, carminite, scorodite, anglesite, goethite, quartz, and gartrellite itself. ## Localities The most important and best-documented occurrences of this very rare mineral are: - Clara Mine, Rankach Valley, Wolfach, Black Forest, Germany (type locality). - Guldener Hirsch Mine, Schneeberg, Saxony, Germany. - Preguiça Mine, Sobral da Adiça, Moura, Portugal.

Rarity

Very rare

For collectors

## Quality Criteria The quality of phosphogartrellite specimens is primarily assessed based on the richness and aesthetics of the crystal aggregates. Most valued are specimens with clearly formed, rosette-like clusters of intense green color, contrasting with the rock matrix. Due to the microscopic size of the crystals, their abundance on the specimen's surface is crucial. The clarity and size of individual crystals are less important, as they are inherently very small. ## Popular Localities The most known and valued specimens, considered the best for this species, come from the type locality – the Clara Mine in the Black Forest, Germany.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Due to the extreme fragility and small size of the crystals, mechanical contact (even with a soft brush) is highly risky. The use of water, especially with detergents, is discouraged. ## What to Avoid Contact with all chemicals, including acids and bases, which can destroy the mineral, must be strictly avoided. The crystals are very brittle and sensitive to ultrasound. Specimens should be protected from shocks, impacts, and abrasion. ## Storage It is recommended to store specimens in closed, stable containers (micromount type) to protect them from dust, mechanical damage, and sudden changes in humidity. Display should be away from sources of vibration.

Sources

Read more