How to identify Kyanite

To correctly identify Kyanite (Kyanite), 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

   Typically blue, often with color zoning (darker blue in the center, lighter blue or white on the edges). Can also be white, gray, green, or black.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous to pearly.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Bladed or columnar crystals, often intergrown. Can be massive.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically forms elongated, bladed crystals, often flattened. Crystals are triclinic.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect cleavage parallel to {100} and good cleavage parallel to {010}. This often results in splintery or fibrous fragments.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in regionally metamorphosed pelitic rocks such as schists, gneisses, and granulites. Also occurs in some eclogites and quartz veins.

Key Facts

Hardness

4.5-5 parallel to length, 6-7 perpendicular to length (Mohs scale)

Specific Gravity

3.53-3.67

Crystal System

Triclinic

Color

Blue, white, gray, green, black; often color-zoned

Luster

Vitreous to pearly

Transparency

Transparent to translucent

Fracture

Splintery, uneven

Cleavage

Perfect on {100}, good on {010}

Composition

Aluminum silicate (Al2SiO5)

Physical characteristics

• Crystal Habit: Bladed, columnar, massive, fibrous
• Cleavage Type: Perfect in one direction ({100}), good in another ({010})
• Fracture Type: Splintery to uneven
• Tenacity: Brittle
• Luster Type: Vitreous to pearly

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