How to identify Topaz or Aquamarine (Beryl)

To correctly identify Topaz or Aquamarine (Beryl) (Mineral (likely Topaz or Beryl)), 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

   Topaz: Colorless, white, pale blue, yellow, orange, pink, brown, rarely red. Aquamarine: Blue to blue-green. The color of both can be influenced by trace elements and irradiation. Natural blue topaz is rare; most blue topaz is heat-treated and irradiated. Aquamarine's blue color is due to Fe2+.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to sub-vitreous.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth, often with conchoidal fracture surfaces.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Topaz: Orthorhombic system, typically forming prismatic crystals with pyramidal and basal terminations. Often striated parallel to the c-axis. Beryl: Hexagonal system, typically forming hexagonal prisms, often with flat basal terminations. Striations parallel to the c-axis are common.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Topaz: Perfect basal cleavage (one direction). Beryl: Imperfect basal cleavage (one direction), often not observed in faceted stones.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Both are found in granitic pegmatites, greisens, and hydrothermal veins. Topaz can also occur in rhyolite cavities. Beryl is also found in some mica schists and alluvial deposits.

Key Facts

Hardness

Topaz: 8 on Mohs scale. Beryl: 7.5-8 on Mohs scale.

Specific Gravity

Topaz: 3.4-3.6 g/cm³. Beryl: 2.65-2.80 g/cm³.

Crystal System

Topaz: Orthorhombic. Beryl: Hexagonal.

Color

Topaz: Colorless, blue, yellow, orange, pink, brown. Aquamarine: Blue to blue-green.

Luster

Vitreous.

Transparency

Transparent to translucent.

Fracture

Topaz: Conchoidal to uneven. Beryl: Conchoidal to uneven.

Cleavage

Topaz: Perfect basal (one direction). Beryl: Imperfect basal (one direction).

Composition

Topaz: Aluminum silicate fluoride hydroxide. Beryl: Beryllium aluminum cyclosilicate.

Physical characteristics

• Crystal Habit: Topaz: Prismatic crystals, often with striations parallel to the c-axis. Beryl: Hexagonal prisms, often with flat basal terminations, also striated parallel to the c-axis.
• Cleavage Type: Topaz: Perfect basal {001}. Beryl: Imperfect basal {0001}.
• Fracture Type: Conchoidal to uneven.
• Tenacity: Brittle.
• Luster Type: Vitreous.

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