How to identify Amethyst

To correctly identify Amethyst (Quartz variety Amethyst), 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

   Violet to deep purple, sometimes with reddish or bluish tints. Color zoning 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 are smooth.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically forms hexagonal prisms terminated by rhombohedral faces. Often found as drusy coatings or large geode linings.

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 granitic) and metamorphic rocks. Often associated with other quartz varieties, chalcedony, and various zeolites.

Key Facts

Hardness

7 on the Mohs scale

Specific Gravity

2.65 g/cm³

Crystal System

Trigonal

Color

Violet to deep purple

Luster

Vitreous

Transparency

Transparent to translucent

Fracture

Conchoidal

Cleavage

None

Composition

Silicon Dioxide (SiO2) with trace iron impurities

Physical characteristics

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

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