Phosphocyclite-(Ni)

Chemical formula: Ni<sup>2+</sup><sub>2</sub>(P<sub>4</sub>O<sub>12</sub>)

Phosphocyclite-(Ni) is a very rare nickel phosphate, forming microscopic, green crystals with a vitreous luster.

## Characteristics Phosphocyclite-(Ni) is a hydrated nickel phosphate belonging to the phosphocyclite group. It occurs as very small, platy or bladed crystals, rarely exceeding 0.2 mm in length. These crystals most often form radial aggregates or small, rosette-like clusters on the surface of other minerals. Due to its microscopic size, it is a mineral primarily accessible to specialized collectors and scientific institutions. ## Physical Properties Phosphocyclite-(Ni) crystals are characterized by a vitreous luster. They are transparent to translucent. Hardness and density have not been precisely measured due to the small size of the samples, but they are estimated based on analogy to other phosphates. ## Colors and Varieties This mineral occurs in a uniform, light green or emerald green color, typical of hydrated nickel compounds. No color or commercial varieties are distinguished. ## History and Name Phosphocyclite-(Ni) was first described in 2017 by a team of mineralogists (Kampf, A.R., et al.) based on samples from a base metal mine near Richelsdorf in Hesse (Germany). The name refers to its chemical composition – the dominance of nickel (Ni) – and its structural relationship to other minerals of the phosphocyclite group. It was approved by the International Mineralogical Association (IMA) under number 2017-020.

Properties

Luster
Vitreous
Streak
Light green
Cleavage
Good on {010}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of phosphocyclite-(Ni) is possible almost exclusively by advanced analytical methods, such as Raman spectroscopy or chemical analysis by electron microprobe (EDS/WDS). Visually, in collecting conditions, it can be suspected based on its characteristic light green color, radial aggregates, and co-occurrence with other rare secondary nickel minerals at the type locality. ## Distinguishing from Similar Minerals It can be confused with other secondary, green nickel minerals, such as annabergite or related phosphates. Annabergite often forms acicular or fibrous coatings, while phosphocyclite-(Ni) occurs as small, platy crystals forming rosettes. However, definitive differentiation requires laboratory analysis. ## Crystal Forms It forms thin, platy crystals with a hexagonal or rhombic outline, which combine into radial, star-shaped, or rosette-like aggregates.

Geological environment

## Genesis Phosphocyclite-(Ni) is a secondary mineral that forms in the oxidation (weathering) zones of polymetallic ore deposits. Its crystallization occurs as a result of the reaction of phosphorus-rich solutions with primary nickel-bearing minerals, such as nickeline. It forms under low-temperature conditions, often in voids and fissures in rocks. ## Mineral Associations At the type locality (Richelsdorf, Germany), it co-occurs with other rare secondary minerals such as annabergite, erythrite, pharmacosiderite, gersdorffite, nickeline, scorodite, and quartz. ## Localities The only confirmed and described occurrence of phosphocyclite-(Ni) in the world is its type locality – the dumps of the former mine in the Richelsdorf area, in the Richelsdorfer Gebirge mountains, Hesse, Germany.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of phosphocyclite-(Ni) specimens is primarily assessed based on the richness and aesthetics of the microscopic aggregates. Most valued are samples with well-formed, distinct rosettes or radial crystal clusters, deposited on a contrasting matrix. The size of these aggregates and the absence of mechanical damage, which are difficult to avoid due to the mineral's delicacy, are also important.

Care and storage

## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to the extreme delicacy and small size of the crystals, any mechanical contact, including with water or a soft brush, risks their irreversible destruction. ## What to Avoid Contact with water, chemical agents, ultrasound, and sudden temperature changes should be absolutely avoided. The crystals are very brittle and sensitive to shock. ## Storage It is recommended to store specimens only in sealed, closed "micromount" boxes, protecting them from dust, moisture, and mechanical damage. Exposure should be away from direct sunlight and heat sources.

Sources

Read more