How to identify Tourmaline

To correctly identify Tourmaline (Tourmaline (Elbaite variety for pink, Schorl or Dravite for green)), 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

   Extremely variable; black (Schorl), pink to red (Rubellite Elbaite), green (Verdelite Elbaite, Chromdravite), blue (Indicolite Elbaite), yellow, brown (Dravite), colorless (Achroite Elbaite), or multi-colored (Watermelon Tourmaline).

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous to resinous.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically prismatic crystals, often with distinct vertical striations on prism faces. Can be massive or granular.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hexagonal-trigonal system, typically elongated prismatic crystals with a characteristic rounded triangular cross-section. Terminations can be complex, often hemimorphic.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Indistinct to poor basal cleavage {0001}, often appearing as conchoidal to uneven fracture. This lack of distinct cleavage is a key differentiating feature.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Granitic pegmatites, granites, aplites, hydrothermal veins, metamorphic rocks (schists, gneisses, marbles), and detrital sediments.

Key Facts

Hardness

7-7.5 on the Mohs scale

Specific Gravity

2.82-3.32 (varies with composition, Schorl is higher, Elbaite is lower)

Crystal System

Trigonal

Color

Extremely variable, often pleochroic

Luster

Vitreous to resinous

Transparency

Transparent to opaque

Fracture

Conchoidal to uneven

Cleavage

Indistinct to poor basal cleavage {0001}

Composition

Complex borosilicate of aluminum, iron, magnesium, sodium, lithium, or other elements

Physical characteristics

• Crystal Habit: Prismatic, often elongated, with vertical striations on prism faces; also massive, columnar, or granular. Cross-section is typically a rounded triangle.
• Cleavage Type: Indistinct to poor basal cleavage {0001}. Fracture is more prominent than cleavage.
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle
• Luster Type: Vitreous to resinous

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