How to identify Amethyst

To correctly identify Amethyst (SiO2 (Quartz variety)), 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

   Ranges from pale lilac to deep violet-purple. Color zoning (uneven distribution of color) is common.

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 rough on crystal faces, conchoidal fracture surfaces.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically forms as hexagonal prisms terminating in rhombohedral faces (pyramidal). Can also be massive or granular.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None (lacks cleavage).

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in hydrothermal veins, pegmatites, and especially in geodes and vugs within volcanic rocks (e.g., basalt) and granitic intrusions.

Key Facts

Hardness

7 (Mohs scale)

Specific Gravity

2.65 g/cm³

Crystal System

Trigonal

Color

Violet, purple, often with color zoning

Luster

Vitreous

Transparency

Transparent to translucent

Fracture

Conchoidal

Cleavage

None

Composition

Silicon dioxide (SiO2)

Physical characteristics

• Crystal Habit: Prismatic, often terminated by rhombohedral faces; also massive, granular, drusy.
• Cleavage Type: None (lacks cleavage).
• Fracture Type: Conchoidal (shell-like, curved breaks).
• Tenacity: Brittle.
• Luster Type: Vitreous (glassy).

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