How to identify Fluorite

To correctly identify Fluorite (CaF2), 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: purple, blue, green, yellow, colorless, pink, red, brown, black. Often banded or zoned with multiple colors.

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.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically cubic, often with penetration twins. Octahedral and dodecahedral forms are also common. Can be massive, granular, or botryoidal.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect octahedral cleavage in four directions, producing characteristic triangular or diamond-shaped fragments when broken.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, often associated with metallic ore deposits (e.g., lead, zinc, silver). Also found in pegmatites, carbonatites, and as a gangue mineral in various igneous and metamorphic rocks. Can occur in sedimentary rocks as a diagenetic mineral or in evaporite deposits.

Key Facts

Hardness

4 (Mohs scale)

Specific Gravity

3.18 (variable with impurities, 3.0-3.3)

Crystal System

Isometric (cubic)

Color

Variable: purple, blue, green, yellow, colorless, pink, red, brown, black; often zoned or banded.

Luster

Vitreous (glassy)

Transparency

Transparent to translucent

Fracture

Conchoidal to uneven

Cleavage

Perfect octahedral in four directions {111}

Composition

Calcium Fluoride (CaF2)

Physical characteristics

• Crystal Habit: Cubic, octahedral, dodecahedral; also massive, granular, botryoidal, columnar.
• Cleavage Type: Perfect octahedral {111}
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle
• Luster Type: Vitreous

Explore Fluorite