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Opalite, when referring to the synthetic glass, is a man-made material designed to mimic the appearance of natural opal or moonstone. It typically exhibits a milky, translucent to semi-translucent body with a characteristic blue or bluish-white glow when viewed against a dark background, and an orange or yellowish glow when viewed against a light background or with transmitted light. This optical effect is known as adularescence or opalescence, though it differs fundamentally from the play-of-color (diffraction) seen in precious natural opal. Chemically, it is a type of glass, not a mineral, and lacks the ordered atomic structure of true minerals.
How to Identify
- Color
- Typically milky white, bluish-white, or pale blue with an internal orange or yellowish glow when backlit. The blue hue is more prominent against dark backgrounds, while the orange/yellow is seen with transmitted light.
- Luster
- Vitreous (glassy) to waxy.
- Texture
- Smooth, conchoidal fracture surfaces.
- Crystal Form
- Amorphous (no crystal form, as it is glass).
- Cleavage
- None (exhibits conchoidal fracture).
- Geological Environment
- Not found in geological environments; it is manufactured in industrial settings.
Key Facts
- Hardness: 5.5-6 on the Mohs scale.
- Specific Gravity: Approximately 2.65-2.80.
- Crystal System: Amorphous (non-crystalline).
- Color: Milky white, pale blue, with internal orange/yellow glow.
- Luster: Vitreous (glassy).
- Transparency: Translucent to semi-translucent.
- Fracture: Conchoidal (shell-like, curved breaks).
- Cleavage: None.
- Composition: Primarily silicon dioxide (SiO2) with various metal oxides (e.g., Al2O3, CaO, Na2O) as additives and opacifying agents.
Quick Check
- Color: Milky white to pale blue with internal orange/yellow glow when backlit.
- Luster: Vitreous (glassy).
- Streak: White (as it is glass, it will not produce a streak on a streak plate).
Physical Characteristics
- Crystal Habit: Massive, amorphous (as it is glass).
- Cleavage Type: None.
- Fracture Type: Conchoidal.
- Tenacity: Brittle.
- Luster Type: Vitreous.
Formation
Opalite, in the context of synthetic opal glass, is formed through an industrial process involving the melting and cooling of various glass-forming oxides, primarily silica (SiO2), often with the addition of other metal oxides (e.g., aluminum oxide, calcium oxide, sodium oxide) and opacifying agents. The characteristic opalescent or adularescent effect is achieved by introducing microscopic inclusions or by controlling the cooling process to induce phase separation, creating light-scattering centers within the glass matrix. It is not a naturally occurring mineral or rock.
Usage
Primarily used in jewelry (beads, cabochons, carvings), decorative objects, and sometimes as an imitation for natural opal or moonstone. Its attractive play of color and affordability make it popular in costume jewelry and metaphysical markets.
Age Distribution
Modern (manufactured)
Where to Find
Manufacturing Facilities
Opalite (synthetic glass) is produced in glass manufacturing plants worldwide, particularly in regions with established glass industries.
Jewelry Stores and Craft Markets
Commonly found in retail outlets selling jewelry, beads, and decorative items, often marketed as 'Opalite' or 'Sea Opal'.
Finding Tips
Check for Bubbles
Examine the material closely for small, spherical gas bubbles, which are characteristic of glass and not found in natural opal or moonstone.
Observe Optical Effects
Note the distinct blue glow against dark backgrounds and orange/yellow glow when backlit. Natural opal exhibits a 'play-of-color' (diffraction of light into spectral colors), while moonstone shows adularescence (a schiller or billowy light effect) that is typically silvery-white to bluish, not the distinct blue/orange shift of Opalite glass.
Hardness Test (with caution)
Opalite glass typically has a Mohs hardness of 5.5-6. This can help distinguish it from natural opal (5.5-6.5) and moonstone (6-6.5), though this test is not definitive and can damage the material.
Specific Gravity
Opalite glass generally has a specific gravity around 2.65-2.80, which can be higher than natural opal (1.98-2.25) and similar to moonstone (2.56-2.59). This requires specialized equipment.
Similar Rocks
Natural Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Also known as: Precious Opal, Common Opal
Moonstone
Orthoclase Feldspar ((K,Na)AlSi3O8)
Also known as: Adularia, Hecatolite
Chalcedony
Cryptocrystalline Quartz (SiO2)
Also known as: Agate, Jasper, Carnelian
Scientific Classification
- Mineral Class
- Not a mineral; it is a synthetic glass.
- Group
- Synthetic Glass
- Crystal System
- Amorphous
- Chemical Formula
- Variable, typically (SiO2)x(Al2O3)y(CaO)z(Na2O)w...
- Composition
- Complex mixture of silicon dioxide and various metal oxides.
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