How to identify Amethyst

To correctly identify Amethyst (SiO2 (Amethyst variety of Quartz)), 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 brownish undertones. 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 and curved.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically forms as hexagonal prisms terminated by rhombohedral faces. Often found as drusy coatings or in geode formations. Can also be massive.

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, geodes, vugs in volcanic rocks (especially basalts), and sometimes in pegmatites or metamorphic rocks.

Key Facts

Hardness

7 on the Mohs scale

Specific Gravity

2.65 g/cm

Crystal System

Trigonal

Color

Violet to deep purple

Luster

Vitreous

Transparency

Transparent to translucent

Fracture

Conchoidal

Cleavage

None

Composition

Silicon dioxide (SiO2)

Physical characteristics

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

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