UV-Reactive Hyalite Opal with Polished Base – Zacatecas, Mexico – 28 grams

A vivid UV-Reactive Hyalite Opal specimen from Zacatecas, Mexico, featuring translucent, glassy opal arranged in rounded botryoidal formations over contrasting dark volcanic matrix. The natural opal surface has been preserved, while the base has been cut and polished to create a stable freestanding display.

Under visible light, the hyalite appears colorless to softly translucent with a wet, glass-like luster. Rounded droplets and overlapping bulbous formations create a sculptural surface filled with internal textures, reflections, and subtle natural inclusions.

Under ultraviolet illumination, the opal transforms into an exceptionally bright neon-green display. This dramatic fluorescence is characteristic of many hyalite opals from Zacatecas and is generally associated with trace uranium compounds incorporated into the opal during formation. Fluorescence may vary in color and intensity depending on the wavelength and strength of the UV lamp used.

Measuring approximately 1 × 1 × 1.25 inches and weighing 28 grams, this compact specimen offers remarkable visual impact. Its glassy natural formation, contrasting matrix, polished base, and intense UV response make it an excellent addition to an opal collection or fluorescent-mineral display.

Specifications

Mineral: Hyalite Opal

Mineral Group: Opal

Locality: Zacatecas, Mexico

Weight: 28 grams (approximately 0.06 lbs)

Dimensions: Approximately 1 × 1 × 1.25 inches

Color in Visible Light: Colorless to translucent with subtle milky areas

UV Response: Intense neon-green fluorescence

Crystal Habit: Rounded botryoidal and globular opal formation

Luster: Vitreous to glassy

Transparency: Transparent to translucent

Composition: Hydrated amorphous silica

Matrix: Dark volcanic host rock

Finish: Natural opal surface with a cut and polished base

Display: Freestanding thumbnail specimen

Condition: Natural mineral specimen with inherent inclusions, contacts, and surface variations

Exact specimen shown

About Hyalite Opal

Hyalite is a transparent to translucent variety of common opal recognized for its exceptionally glassy appearance. Its name comes from the Greek word hyalos, meaning glass. Unlike precious opal, hyalite generally does not display play-of-color; its collector appeal comes from its clarity, rounded growth forms, glossy luster, and frequent fluorescence.

Opal is composed of hydrated amorphous silica, commonly represented as SiO₂·nH₂O. Because it lacks the orderly internal crystal structure of crystalline quartz, opal is classified as a mineraloid rather than a true crystalline mineral.

Hyalite commonly forms as rounded droplets, crusts, and botryoidal masses where silica-rich fluids deposit opal within openings in volcanic rocks. Specimens from Zacatecas are especially prized for their brilliant green response under ultraviolet light.

The green fluorescence is typically attributed to trace uranyl ions incorporated during formation. This is a naturally occurring mineralogical feature and should not be interpreted as artificial coloring or treatment. As with all collectible mineral specimens, it is best handled responsibly, kept away from children and pets, and not ground, cut, or ingested.

Collector Notes

This specimen features:

• Natural hyalite opal from Zacatecas, Mexico
• Strong neon-green fluorescence under UV illumination
• Colorless to translucent appearance in visible light
• Rounded botryoidal and globular growth
• Bright glass-like surface luster
• Contrasting dark volcanic matrix
• Natural opal surface preserved
• Cut and polished base for stable freestanding display
• Dramatic visible-light and UV-light transformation
• Compact thumbnail size with exceptional visual impact
• Classic fluorescent Mexican opal
• One-of-a-kind natural mineral formation
• Exact specimen pictured

Perfect for collectors of hyalite opal, Mexican opal, fluorescent minerals, UV-reactive crystals, Zacatecas minerals, botryoidal formations, volcanic minerals, polished-base specimens, thumbnail minerals, and unusual natural opal.

Professionally packaged and shipped from Colorado.

You will receive the exact specimen shown.

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