How to identify African Turquoise

To correctly identify African Turquoise (Jasper (often treated or dyed)), 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 mottled green to blue-green, often with dark brown, black, or reddish-brown matrix-like inclusions. The color is frequently enhanced by dyeing.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Dull to vitreous (glassy) on fractured surfaces, often waxy or resinous when polished.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Fine-grained, dense, and opaque. Can feel smooth when polished.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Massive, cryptocrystalline aggregates; individual crystals are microscopic and not visible to the naked eye.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, due to its cryptocrystalline nature.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Jasper deposits are found in various geological settings, including volcanic rocks, sedimentary beds, and hydrothermal veins. The specific jasper used for 'African Turquoise' is typically sourced from regions in Africa, often associated with volcanic or sedimentary formations where silica-rich fluids have precipitated.

Key Facts

Hardness

6.5-7 on the Mohs scale (for jasper).

Specific Gravity

2.58-2.91 (for jasper).

Crystal System

Trigonal (for quartz/chalcedony).

Color

Mottled green, blue-green, often with brown/black/reddish-brown matrix. Color is frequently enhanced.

Luster

Dull to vitreous, waxy, or resinous.

Transparency

Opaque.

Fracture

Conchoidal to uneven.

Cleavage

None.

Composition

Silicon dioxide (SiO2) with various impurities (e.g., iron oxides, clay minerals).

Physical characteristics

• Crystal Habit: Cryptocrystalline, massive, nodular, botryoidal.
• Cleavage Type: None.
• Fracture Type: Conchoidal to uneven.
• Tenacity: Brittle.
• Luster Type: Dull, waxy, or resinous.

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