Freedite
Chemical formula: Cu<sup>1+</sup>Pb<sup>2+</sup><sub>8</sub>(As<sup>3+</sup>O<sub>3</sub>)<sub>2</sub>O<sub>3</sub>Cl<sub>5</sub>
Freedyite is a very rare lead and copper arsenite, forming bright yellow, platy crystals with an adamantine luster.
Description
## Characteristics Freedyite is a halide mineral containing arsenic, lead, and copper. It occurs as small, thin, tabular or platy crystals, often forming rosette-like or fan-shaped aggregates. Its most distinctive features are its pale yellow, canary yellow, or greenish-yellow color and a strong, adamantine luster on crystal faces. ## Physical Properties This mineral is relatively soft, with a Mohs hardness ranging from 3 to 4.5. It is also extremely dense, with a specific gravity of approximately 7.1 g/cm³, which is noticeable even in small specimens. It exhibits perfect, unidirectional cleavage. It is translucent. ## Colors and Varieties Freedyite occurs in shades of yellow – from pale yellow to intense canary yellow, sometimes with a greenish tint. No color or commercial varieties are distinguished. ## History and Name The mineral was first described in 1984 by Pete J. Dunn and Roland C. Rouse. Its name honors Robert L. Freed (born 1938), a professor of geology at Trinity University in Texas, for his contributions to the mineralogy research of the Långban deposit in Sweden, where this mineral originates. ## Uses Due to its extreme rarity and toxic chemical composition (lead and arsenic content), freedyite has no industrial applications. It is solely an object of interest for advanced mineral collectors and scientific institutions.
Diagnostic features
## Identification Key diagnostic features of freedyite include its characteristic platy crystal habit, bright yellow color, adamantine luster, and very high density. Its occurrence is almost exclusively limited to one locality in the world, which is a strong identification clue. ## Distinguishing from Similar Minerals Freedyite is sometimes confused with other yellow secondary minerals. It differs from mimetite by its lower hardness and different crystal habit (mimetite forms hexagonal prisms). It differs from wulfenite by its habit (wulfenite forms square tablets) and usually paler color. A density test helps distinguish it from most visually similar minerals. ## Crystal Forms It forms thin, tabular crystals with pseudohexagonal outlines. These crystals most often occur as small, radial or fan-shaped aggregates, as well as scaly coatings.
Geological environment
## Genesis Freedyite is a secondary mineral formed in the oxidation zones of polymetallic deposits that have undergone metamorphic processes. It forms within altered carbonate rocks (limestones and dolomites). ## Mineral Associations This mineral co-occurs with other rare minerals from the Långban deposit, such as magnussonite, mimetite, franklinite, willemite, and calcite. ## Localities The only significant and historical locality for well-formed freedyite crystals is the Långban mine in Filipstad Municipality, Värmland region, Sweden. This is its type locality.
Rarity
Very rare
Collector aspects
## Quality Criteria The most highly valued freedyite specimens are those with well-formed, sharply terminated plates of intense, canary yellow color and strong luster. The size of the aggregates and the richness of their occurrence on the rock matrix are also important. Specimens with associated rare Långban minerals are particularly sought after. ## Popular Localities For collectors, the only significant source of freedyite specimens is the historic Långban locality in Sweden. Specimens from this locality are considered mineralogical classics.
Care and storage
## Cleaning Freedyite specimens should only be dry-cleaned, using a soft brush to remove dust. Due to its excellent cleavage and softness, mechanical and ultrasonic cleaning should be avoided. ## What to Avoid The mineral is sensitive to chemicals, especially acids. Contact with water and all cleaning fluids should be avoided. Due to its lead and arsenic content, it is toxic – avoid inhaling dust and wash hands after any contact with the specimen. ## Storage Freedyite should be stored in stable conditions, away from moisture and direct sunlight. The safest method is to keep it in a closed "micromount" box, which protects delicate crystals from damage and limits contact with the toxic mineral.