Pattersonite

Chemical formula: Pb₂+Fe₃+₃(PO₄)₂(OH)₅(H₂O)

Pattersonite is a very rare hydrated lead iron phosphate, forming tiny, tabular crystals of brown color and vitreous luster.

## Characteristics Pattersonite is a very rare mineral from the phosphate group, chemically classified as a hydrated lead iron phosphate. It occurs as very small, thin, tabular crystals with a hexagonal outline, rarely exceeding 0.2 mm. These crystals often form rosette-like or spherical aggregates. Due to its size, it is a mineral primarily accessible to specialized micromineral collectors. ## Physical Properties Pattersonite crystals exhibit a vitreous luster. They are brittle, and their hardness and density have not been precisely determined due to the small size of the samples. The mineral is translucent. ## Colors and Varieties Pattersonite has a characteristic brown to reddish-brown color. No color varieties or commercial varieties are known. ## History and Name The mineral was named after Dr. Joseph E. Patterson (born 1939), an American chemist and micromineral collector, who first found this mineral. It was approved by the International Mineralogical Association (IMA) in 2000. The type locality is the Foote Lithium Co. mine in the Kings Mountain area of North Carolina, USA. ## Applications Pattersonite has no industrial applications. Its significance is purely scientific and collectible, especially among micromineral collectors.

Properties

Mohs hardness: 4
Color: Dark yellow
Luster: Vitreous
Streak: very pale yellow
Density: 4.04
Cleavage: one poor cleavage of unknown orientation
Fracture: Conchoidal
Transparency: Translucent
Crystal system: Triclinic

Diagnostic features

## Identification Identifying pattersonite under amateur conditions is practically impossible. It requires specialized analytical equipment, such as energy-dispersive spectroscopy (EDS/EDX) or X-ray diffraction (XRD), to confirm its chemical composition and structure. Visually, it can be suspected based on its brown color, tabular crystal habit, and co-occurrence with other rare phosphates in pegmatites. ## Distinguishing from Similar Minerals Pattersonite can be confused with other fine-grained, brown phosphates, such as beraunite, rockbridgeite, or dufrenite. Definitive differentiation is only possible using advanced analytical methods. The habit of thin, hexagonal tablets is a characteristic feature, but not unique. ## Crystal Forms The mineral forms very small, thin, tabular crystals with a hexagonal outline. These crystals often combine into rosette-like, spherical, or irregular aggregates.

Geological environment

## Genesis Pattersonite is a secondary mineral that forms in complex, granitic pegmatites. It forms as a result of hydrothermal processes or weathering, which lead to the alteration of primary phosphate minerals in the presence of iron- and lead-rich solutions. ## Mineral Associations At the type locality (Foote mine), pattersonite co-occurs with minerals such as rockbridgeite, strengite, leucophosphite, montgomeryite, wardite, quartz, and microcline. ## Localities The only confirmed and described occurrence of pattersonite in the world is its type locality: Foote Lithium Co. mine, Kings Mountain district, Cleveland County, North Carolina, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria For micromineral 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 rare associated minerals are also important. Due to its microscopic size, clarity and transparency are not key criteria. ## Popular Localities The only source of pattersonite specimens is the Foote mine in North Carolina, USA. This is a classic locality for many rare phosphate minerals, and specimens from there are highly prized by specialists.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Due to the extreme brittleness and small size of the crystals, contact with water, brushes, or ultrasonics is highly inadvisable and can lead to the destruction of the specimen. ## What to Avoid All chemicals, including acids and bases, should be avoided. The mineral is sensitive to shocks and mechanical damage. It should not be heated or exposed to strong light sources that could cause thermal changes. ## Storage Pattersonite specimens should be stored exclusively in specialized micromount boxes, which protect them from dust, moisture, and mechanical damage. Display is only possible under a microscope.

External references

https://www.mindat.org/min-28951.html