How to identify Indicolite

To correctly identify Indicolite (Indicolite (Elbaite variety)), 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 light blue to deep blue, often with greenish or violet tints. Strong pleochroism is characteristic, showing different shades of blue or even blue-green depending on the viewing angle.

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 rough on crystal faces, often exhibiting prominent striations parallel to the length of the crystal.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically forms elongated, prismatic crystals with a characteristic triangular cross-section (due to the trigonal crystal system). Crystals often have rounded edges and may be terminated by complex pyramidal or pedion faces. Can also occur as massive or columnar aggregates.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Indicolite, like other tourmalines, has very poor to indistinct cleavage, making it prone to conchoidal or uneven fracture rather than clean breaks along crystallographic planes.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Primarily found in complex granitic pegmatites, which are intrusive igneous rocks. Also occurs in some hydrothermal veins and regionally metamorphosed rocks, particularly schists and gneisses, where boron-rich fluids were present.

Key Facts

Hardness

7-7.5 on the Mohs scale

Specific Gravity

3.03-3.10 (variable depending on composition)

Crystal System

Trigonal

Color

Blue, often with pleochroism (different colors from different angles)

Luster

Vitreous to resinous

Transparency

Transparent to translucent

Fracture

Conchoidal to uneven

Cleavage

Very poor to indistinct

Composition

Complex borosilicate of aluminum, lithium, and iron, with varying amounts of other elements (Na, Ca, Mg, F, OH)

Physical characteristics

• Crystal Habit: Prismatic, often elongated, with vertical striations on prism faces; typically forms three-sided or six-sided prisms with rounded edges; terminations can be complex pyramidal or pedion.
• Cleavage Type: Very poor to indistinct, typically parting along basal planes or rhombohedral planes, but rarely observed.
• Fracture Type: Conchoidal to uneven, brittle.
• Tenacity: Brittle
• Luster Type: Vitreous (glassy) to resinous

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