How to identify Amethyst

To correctly identify Amethyst (Quartz variety (SiO2)), 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 can be unevenly distributed, often concentrated at the crystal tips.

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, depending on growth conditions.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically forms as hexagonal prisms terminated by rhombohedral faces (pyramidal). Often found as drusy coatings or large crystals within geodes.

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

   Hydrothermal veins, vugs, and geodes within igneous (especially basaltic) and metamorphic rocks. Also found in alluvial deposits.

Key Facts

Hardness

7 (Mohs scale)

Specific Gravity

2.65 g/cm

Crystal System

Trigonal

Color

Violet, purple, often with color zoning

Luster

Vitreous

Transparency

Transparent to translucent

Fracture

Conchoidal

Cleavage

None

Composition

Silicon dioxide (SiO2) with trace iron impurities

Physical characteristics

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

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