Wherryite

Chemical formula: Pb²⁺₇Cu²⁺₂(S⁶⁺O₄)₄(SiO₄)₂(OH)₂

Wherryite is a very rare lead-copper sulfate and silicate, forming microscopic, blue-green crystals.

## Characteristics Wherryite is a complex lead-copper sulfate and silicate. It occurs as very small, tabular or bladed crystals, rarely exceeding 1 mm in length. It typically forms disseminated aggregates, coatings, or occurs in druses of fine crystals on the host rock. Its characteristic, vivid blue-green color makes it recognizable despite its small size. ## Physical Properties Wherryite crystals exhibit a luster described as vitreous to resinous. They are transparent to translucent. Due to the small size of the crystals, hardness is difficult to measure precisely but is estimated at around 3 on the Mohs scale. It is a mineral with high density (6.45 g/cm³), which is typical for lead-bearing minerals. ## Colors and Varieties This mineral occurs in a uniform, characteristic blue-green or green-blue color. No color or commercial varieties are known. ## History and Name The name wherryite comes from the surname of Edgar Theodore Wherry (1885-1982), an American mineralogist, soil scientist, and botanist, who first studied this mineral. It was formally described as a new mineral species in 1950 by Joseph Murdoch and Robert W. Webb based on samples found in the Mammoth-St. Anthony mine in Arizona, USA. ## Uses Wherryite has no industrial application. Its significance is purely scientific and collectible, being an object of desire for specialized collectors of rare minerals.

Properties

Mohs hardness
3
Color
Light green, yellow or bright yellowish-green.
Luster
Vitreous
Streak
Light green
Density
6.45
Cleavage
Good on {001}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Diagnostic features of wherryite include its characteristic blue-green color, occurrence as very small, tabular crystals, and co-occurrence with other rare lead minerals in oxidation zones. Due to the microscopic size of the crystals, definitive identification requires advanced analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals Wherryite can be confused with other secondary copper and lead minerals of similar color, such as linarite, caledonite, or diaboleite. Distinguishing it with the naked eye is practically impossible. Linarite usually has a more intensely blue color, and caledonite often forms larger crystals. Diaboleite crystallizes in a different system (tetragonal) and has different optical properties. However, certain differentiation requires laboratory analysis. ## Crystal Forms Wherryite forms very small, thin, tabular crystals with a hexagonal outline or bladed habit. These crystals often occur as disseminated units or form small, radial aggregates and druses in rock cavities.

Geological environment

## Genesis Wherryite is a secondary mineral formed in the oxidation zones of polymetallic deposits rich in lead, copper, and sulfides. It forms as a result of surface water action on primary ore minerals under desert conditions (dry and hot climate). ## Mineral Associations This mineral occurs in association with other rare secondary minerals. It most commonly co-occurs with cerussite, diaboleite, phosgenite, boleite, linarite, wulfenite, hemimorphite, and chrysocolla. ## Localities The most important and historical occurrence of wherryite is its type locality - the Mammoth-St. Anthony mine in Pinal County, Arizona, USA. This is the main source of the best-known specimens. This mineral has also been identified in several other locations worldwide, including mines in the Tiger area of Arizona, but these occurrences are of much lesser significance.

Rarity

Very rare

For collectors

## Quality Criteria The quality of a wherryite specimen primarily depends on the size and development of the crystals, which is a rarity. The most prized specimens are those with visible, sharp, undamaged crystals of intense blue-green color, set on a contrasting rock matrix. The richness of the aggregate is also important - the more crystals on a given rock fragment, the more attractive the specimen. Due to the microscopic nature of the mineral, most specimens are referred to as "micromounts." ## Popular Localities By far the most valued and sought-after specimens come from the only significant locality in the world: the Mammoth-St. Anthony mine in Tiger, Pinal County, Arizona, USA. Specimens from this locality are considered classic and serve as the benchmark for this mineral.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Due to the softness and fragility of the crystals, contact with water, and especially mechanical cleaning (e.g., with a brush), is absolutely inadvisable and can lead to the destruction of specimens. ## What to Avoid Avoid contact with any chemicals, including acids and detergents. The mineral is sensitive to changes in temperature and humidity. It should not be heated or exposed to direct sunlight, which can cause its degradation. As a lead-bearing mineral, avoid inhaling dust and wash hands after contact with the specimen. ## Storage Wherryite specimens should be stored under stable conditions, preferably in closed, padded "micromount" boxes that protect them from mechanical damage, dust, and sudden changes in humidity. It should be kept away from sources of heat and light.

External references

Sources

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