How to identify Heliodor

To correctly identify Heliodor (Beryl (variety Heliodor)), 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

   Yellow, golden-yellow, greenish-yellow. The color is typically uniform but can show slight zoning.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy).

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth to slightly uneven on fracture surfaces.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically forms hexagonal prisms, often with striations parallel to the c-axis. Terminations can be flat basal pinacoids or pyramidal faces.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Imperfect basal cleavage {0001}, often not observed in fractured specimens.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Granitic pegmatites, hydrothermal veins, and greisens associated with granitic intrusions. Often found alongside quartz, feldspar, muscovite, and other pegmatite minerals.

Key Facts

Hardness

7.5-8 on Mohs scale

Specific Gravity

2.65-2.80 g/cm³

Crystal System

Hexagonal

Color

Yellow, golden-yellow, greenish-yellow

Luster

Vitreous

Transparency

Transparent to translucent

Fracture

Conchoidal to uneven

Cleavage

Imperfect basal {0001}

Composition

Beryllium aluminum cyclosilicate (Be3Al2Si6O18)

Physical characteristics

• Crystal Habit: Prismatic, typically hexagonal prisms, often striated parallel to the c-axis. Can also be massive or granular.
• Cleavage Type: Imperfect basal {0001}. Often not observed in hand specimens or fractured material.
• Fracture Type: Conchoidal to uneven. This is the more common breakage pattern.
• Tenacity: Brittle
• Luster Type: Vitreous (glassy)

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