Glass-(Dy)

Chemical formula: Pb(Dy,Y,Ca)Al₂(AsO₄)₂(OH,O)₅

Glass-(Dy) is a rare lead and dysprosium arsenate, forming small, hexagonal crystals of a pale yellow color.

## Characteristics Glass-(Dy) is an arsenate belonging to the microlite group. It occurs as very small, hexagonal, tabular crystals, rarely exceeding 0.3 mm in size. It typically forms aggregates or single, scattered crystals on the surface of other minerals. Its pale yellow to yellowish-green color is characteristic. ## Physical Properties The crystals exhibit a strong, vitreous luster. The mineral is relatively dense due to its lead and dysprosium content. It is transparent to translucent. Hardness has not been precisely measured but is estimated to be around 4 on the Mohs scale. ## Colors and Varieties Glass-(Dy) occurs in shades from pale yellow to yellowish-green. No color varieties or commercial varieties are known. ## History and Name The mineral was named after Charles A. Glass (1924–1998), an American mineral collector from Virginia, who specialized in microminerals. It was officially recognized by the International Mineralogical Association (IMA) in 2021. The suffix -(Dy) indicates the dominance of dysprosium among rare earth elements in its chemical composition. ## Uses Glass-(Dy) has no industrial application. It is solely an object of interest for collectors specializing in rare minerals and microminerals.

Properties

Mohs hardness
4
Luster
Vitreous
Streak
Pale yellow
Density
4.66
Cleavage
None
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Hexagonal

Diagnostic features

## Identification Practical identification of Glass-(Dy) is impossible without advanced laboratory methods, such as energy-dispersive spectroscopy (EDS) or X-ray diffraction (XRD). Preliminary identification under a microscope is based on observing small, hexagonal, tabular crystals with a pale yellow color and vitreous luster, occurring in association with other rare arsenates. ## Distinguishing from Similar Minerals It can be confused with other minerals from the microlite group, especially agardite, after which it forms pseudomorphs, as well as with other rare arsenates of similar color and form. Definitive differentiation requires chemical analysis to confirm the dominance of dysprosium. ## Crystal Forms It forms hexagonal, tabular crystals, often gathered in rosette-like or radial aggregates. It also occurs as pseudomorphs after acicular agardite crystals.

Geological environment

## Genesis Glass-(Dy) is a secondary mineral, formed in the oxidation (weathering) zones of polymetallic deposits rich in arsenic and rare earth elements. It forms as a result of the interaction of hydrothermal solutions with earlier minerals. ## Mineral Associations It most commonly co-occurs with agardite-(Y), agardite-(Nd), cheryanovite, quartz, fluorite, kankite, and pharmacosiderite. It often forms pseudomorphs after agardite. ## Localities The only confirmed occurrence (type locality) of this mineral is the Arsenatnaya mine in the Verkhnee mining complex, in the Dzhungar Alatau mountains, Almaty region, Kazakhstan.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a Glass-(Dy) specimen is primarily assessed based on the richness and visibility of crystals on the rock matrix. Specimens with well-formed, clearly visible hexagonal crystals or their radial aggregates under a microscope are most valued. Due to their microscopic size, the clarity and size of individual crystals are of secondary importance. ## Popular Localities The only source of specimens is the type locality in Kazakhstan. All specimens available on the collector's market originate from this single mine.

Care and storage

## Cleaning Due to the extreme rarity and fragility of specimens, mechanical or chemical cleaning is not recommended. Any contaminants, such as dust, can be removed very carefully using a photographic blower bulb. ## What to Avoid Avoid contact with water, acids, detergents, and all chemicals. Do not subject it to ultrasonic cleaning. Protect from high temperatures and sudden temperature changes. ## Storage Glass-(Dy) specimens are microscopic and are usually stored in specialized, sealed micro-mount boxes. Protect from dust and mechanical damage.

Sources

Read more