Paulmooreite

Chemical formula: Pb<sup>2+</sup><sub>2</sub>As<sup>3+</sup><sub>2</sub>O<sub>5</sub>

Paulmooreite is a very rare lead arsenite, forming colorless to pale yellow, tabular crystals with an adamantine luster.

## Characteristics Paulmooreite is a lead arsenite, occurring as small, tabular or bladed crystals that rarely exceed 1 mm in length. It typically forms small aggregates or single, dispersed crystals on the surface of the host rock. It is a transparent mineral with a strong, almost adamantine luster, which distinguishes it from many other secondary minerals. ## Physical Properties Paulmooreite crystals are very soft and brittle, with a Mohs hardness of 3. The mineral is characterized by a high density (6.47 g/cm³), which is typical for lead-bearing minerals. The luster is strongly vitreous to adamantine. It is transparent. ## Colors and Varieties Paulmooreite is most often colorless, but can exhibit pale yellow to canary yellow hues. No named varieties of this mineral have been distinguished. ## History and Name The mineral was discovered in the Långban mine in Sweden and described in 1979 by Pete J. Dunn, Roland C. Rouse, and Joseph A. Nelen. It was named in honor of Paul Brian Moore (1940–2023), an American mineralogist from the University of Chicago, in recognition of his contributions to the study of Långban minerals and complex oxides. ## Uses Paulmooreite has no industrial application. It is of purely scientific and collector's interest as a very rare and well-defined mineral species.

Properties

Mohs hardness
3
Luster
Adamantine
Streak
White
Density
6.47
Cleavage
Good on {010}
Fracture
Uneven
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Paulmooreite can be identified by its characteristic appearance: small, colorless or yellow, tabular crystals with a very strong, adamantine luster. Its occurrence is limited to a specific geological environment – metamorphosed iron and manganese ore deposits. ## Distinguishing from Similar Minerals It can be confused with other rare lead arsenites from Långban, such as magnussonite or finnemanite. Definitive differentiation requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS). Visually, its strong luster and tabular crystal habit distinguish it. ## Crystal Forms Crystals are typically tabular, flattened parallel to {010}, and may exhibit striations. They occur as single, isolated crystals or small, loose aggregates.

Geological environment

## Genesis Paulmooreite is a secondary mineral that forms under metamorphic conditions within iron and manganese ore deposits. It originates in skarns and carbonate rocks that have been subjected to hydrothermal processes. ## Mineral Associations This mineral co-occurs with other rare Långban minerals, such as magnussonite, tegengrenite, hematophanite, hausmannite, mimetite, calcite, and baryte. ## Localities The only confirmed occurrence of paulmooreite in the world is its type locality – the Långban mine in Filipstad Municipality, Värmland region, Sweden. This is a classic locality for many rare minerals.

Rarity

Very rare

For collectors

## Quality Criteria The most prized specimens are those with well-formed, sharp, transparent crystals with intense luster, set on a contrasting matrix. Crystal size is a key factor – specimens with crystals exceeding 0.5 mm are already considered exceptional. The aesthetics of the composition and the absence of damage are also important. ## Popular Localities The only source of paulmooreite specimens is the Långban mine in Sweden. Material from this historic locality is highly sought after by collectors specializing in rare or systematic minerals.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using a soft brush to remove dust. Due to its high brittleness and softness, any contact with water or other chemicals should be avoided. Mechanical cleaning is highly risky. ## What to Avoid Avoid contact with water, acids, and other cleaning agents. The mineral is very soft, so it must be protected from scratching and impacts. It should not be subjected to ultrasonic cleaning. ## Storage Paulmooreite specimens, as microminerals, should be stored in sealed "micromount" boxes, which protect them from dust, mechanical damage, and direct contact. Exposure to moisture should be avoided.

Sources

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