Yeomanite
Chemical formula: Pb²⁺₂O(OH)Cl
Yeomanite is a rare secondary lead mineral, forming colorless to pale yellow crystals, discovered in mines in Arizona.
Properties
- Color
- White, Grey
- Luster
- Subadamantine
- Streak
- White
- Density
- 7.303
- Cleavage
- parallel to the long axis of the fibres but this is masked by the fibrous nature, especially as individual fibres break easily.
- Fracture
- Uneven
- Transparency
- Transparent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Identifying yeomanite in the field is practically impossible without specialized equipment. Identification relies on chemical analysis (EDS) and X-ray diffraction (XRD). In a collection, it can be preliminarily recognized by its characteristic strong luster, crystal form (small, tabular), and association with other rare secondary minerals from Arizona mines. ## Distinguishing from similar minerals Yeomanite can be confused with other colorless or yellowish secondary lead minerals, such as laurionite, paralaurionite, or boleite, with which it often co-occurs. Certain differentiation requires advanced analytical methods, as visual features are very similar, and the crystals are too small for standard tests. ## Crystal forms It forms thin, tabular crystals with hexagonal or octagonal outlines, as well as short prismatic crystals. It occurs as single, scattered crystals or small groups.
Geological environment
## Genesis Yeomanite is a secondary mineral that forms in the oxidation zones of lead deposits. It forms as a result of groundwater reactions with ancient lead smelting slags or in natural weathering zones of lead ores in an arid (desert) climate. ## Mineral associations This mineral co-occurs with other rare, secondary lead halides. At its type locality (Baker mine, Arizona), it was found in association with minerals such as laurionite, paralaurionite, boleite, pseudoboleite, anglesite, and cerussite. ## Localities Yeomanite is an extremely rare mineral, known from only a few localities worldwide. The most important and type locality is the Baker mine in Maricopa County, Arizona, USA. It has also been identified in ancient slags in Lavrion, Greece.
Rarity
Extremely rare
For collectors
## Quality criteria The quality of yeomanite specimens is primarily assessed based on the presence of well-formed, sharp, and undamaged crystals, even if they are microscopic in size. Specimens where crystals are clearly separated and contrast with the matrix are more highly valued. Crystal size, although always small, is also important – any specimen with crystals approaching 1 mm is considered exceptional. The presence of rare associated minerals increases the scientific and collecting value of the specimen. ## Popular localities The only source of collectible yeomanite specimens is its type locality – the Baker mine in Arizona, USA. Specimens from this location are highly sought after by collectors specializing in "micromount" minerals and rare species.
Care and storage
## Cleaning Due to its extreme rarity and delicacy, yeomanite specimens should not be cleaned mechanically or chemically. Any treatment can irreversibly damage the microscopic crystals. If absolutely necessary, compressed air (from a safe distance) can be used to remove loose dust. ## What to avoid Avoid contact with water, acids, detergents, and any other chemicals. The mineral is sensitive to temperature changes and mechanical shocks. Do not touch it with bare hands. ## Storage Yeomanite specimens should be stored exclusively in specialized, sealed "micromount" boxes, protecting them from dust, moisture, and mechanical damage. They should be kept in stable conditions, away from sunlight and heat sources.