UV Fluorescent Hyalite Opal with Polished Base – Zacatecas, Mexico – 37 Grams

A vivid Fluorescent Hyalite Opal specimen from Zacatecas, Mexico, featuring rounded, glass-like opal growth across contrasting reddish-brown volcanic matrix. One side has been polished flat, creating a stable self-standing base while revealing the specimen’s internal structure and the boundary between the hyalite and host rock.

Under ordinary lighting, the hyalite appears colorless to slightly milky with excellent vitreous luster. Rounded botryoidal formations rise across the natural display face, producing a clustered, bubble-like surface that reflects light from numerous angles. Portions of the material are transparent to translucent, allowing the internal textures and underlying matrix to remain visible.

Under ultraviolet illumination, the hyalite transforms into an exceptionally bright electric green. The fluorescence extends across much of the opal formation, clearly outlining individual rounded growths and contrasting dramatically with the comparatively dark matrix. Fluorescent color and intensity may vary depending on the wavelength and strength of the UV lamp, ambient lighting, exposure, and camera settings.

Hyalite opal is a transparent-to-translucent, water-rich form of common opal known for its glassy appearance. The characteristic green fluorescence frequently associated with Mexican hyalite is generally caused by trace uranium present as uranyl compounds. This is a naturally occurring trace-element response and does not mean the specimen is artificially treated. The exact chemistry of this individual specimen has not been analytically tested.

Measuring approximately 1 × 1 × 1 inch and weighing 37 grams, this compact specimen combines strong natural form, brilliant fluorescence, classic Mexican provenance, and convenient self-standing presentation.

Specifications

Mineral: Hyalite Opal

Locality: Zacatecas, Mexico

Weight: 37 grams

Dimensions: Approximately 1 × 1 × 1 inch

Color Under White Light: Colorless to milky white hyalite on reddish-brown matrix

Fluorescence: Intense electric-green response under ultraviolet illumination

UV Disclosure: Fluorescent color and intensity may vary according to UV wavelength, lamp strength, ambient lighting, exposure, and camera settings

Crystal Form: Rounded botryoidal and globular opal growth

Luster: Vitreous to glass-like

Transparency: Transparent to translucent hyalite with opaque matrix

Chemical Composition: Hydrated silica — SiO₂·nH₂O

Mineral Class: Mineraloid

Mohs Hardness: Approximately 5–6.5

Matrix: Natural reddish-brown volcanic host rock

Finish: One side polished flat to create a stable display base and expose the interior structure

Display: Naturally self-standing on its polished base

Condition: Natural mineral specimen with inherent inclusions, contacts, surface textures, matrix variations, internal fractures, and preparation marks along the polished surface

Exact specimen shown

About Hyalite Opal

Hyalite is a transparent or translucent variety of common opal characterized by its colorless appearance, rounded growth forms, and glass-like luster. Unlike precious opal, it generally does not display play-of-color. Its appeal comes from its clarity, sculptural botryoidal formation, and frequent ultraviolet fluorescence.

Opal is a hydrated form of silica containing variable amounts of water. Because it lacks the consistently ordered crystal structure of minerals such as quartz, it is classified as a mineraloid rather than a true crystalline mineral.

Fluorescent hyalite from Mexico is especially prized by ultraviolet-mineral collectors. Trace uranyl compounds commonly act as fluorescent activators, producing a powerful green response under ultraviolet illumination. The precise reaction can differ significantly between shortwave, midwave, and longwave lamps.

Hyalite should be protected from hard impacts, prolonged heat, and sudden temperature changes. Clean gently with a soft dry brush or microfiber cloth and avoid prolonged soaking or harsh chemicals.

Collector Notes

This specimen features:

• Natural hyalite opal from Zacatecas, Mexico
• Intense electric-green UV fluorescence
• Broad fluorescent coverage
• Colorless-to-milky appearance under ordinary light
• Transparent and translucent viewing areas
• Rounded botryoidal opal growth
• Bright glass-like surface luster
• Contrasting reddish-brown volcanic matrix
• Polished surface revealing the internal structure
• Stable self-standing presentation
• Dramatic transformation between white light and UV
• Compact and highly displayable size
• Exact specimen pictured

Perfect for collectors of hyalite opal, fluorescent minerals, Mexican minerals, Zacatecas specimens, botryoidal opal, uranium-activated fluorescence, UV-reactive minerals, polished-base specimens, and compact mineral displays.

Professionally packaged and shipped from Colorado.

You will receive the exact specimen shown.

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