How to identify Opalite

To correctly identify Opalite (Synthetic Opal (Glass)), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.

Step-by-step identification

1. 1

   Color

   Overall color and any zoning or banding

   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.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to waxy.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth, conchoidal fracture surfaces.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Amorphous (no crystal form, as it is glass).

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None (exhibits conchoidal fracture).

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   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.

Physical characteristics

• Crystal Habit: Massive, amorphous (as it is glass).
• Cleavage Type: None.
• Fracture Type: Conchoidal.
• Tenacity: Brittle.
• Luster Type: Vitreous.

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