How to identify Watermelon Tourmaline

To correctly identify Watermelon Tourmaline (Elbaite (a variety of Tourmaline)), 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

   Concentric color zoning with a pink/red core, often a white/clear intermediate zone, and an outer green rind. The colors are typically vibrant and distinct.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to resinous.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth to slightly striated on crystal faces.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically prismatic crystals with characteristic triangular cross-sections (due to the trigonal crystal system) and often exhibiting vertical striations on prism faces. Terminations can be complex, often hemimorphic.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Indistinct to poor basal cleavage, typically parting rather than true cleavage. Fracture is more common.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Granitic pegmatites, particularly lithium-rich types, often found in miarolitic cavities within these pegmatites.

Key Facts

Hardness

7-7.5 on Mohs scale

Specific Gravity

3.02-3.26 (typically around 3.06 for Elbaite)

Crystal System

Trigonal

Color

Concentric pink/red, white/clear, and green zones

Luster

Vitreous to resinous

Transparency

Transparent to translucent

Fracture

Conchoidal to uneven

Cleavage

Indistinct to poor basal cleavage {0001}, often parting

Composition

Sodium Lithium Aluminum Borosilicate Hydroxide

Physical characteristics

• Crystal Habit: Prismatic, often with vertical striations on prism faces; typically long, slender to stout crystals; often hemimorphic terminations.
• Cleavage Type: Poor to indistinct basal cleavage, more commonly exhibits parting along {1011} or {0001}.
• Fracture Type: Conchoidal to uneven, brittle.
• Tenacity: Brittle
• Luster Type: Vitreous (glassy) to resinous

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