How to identify Blue Apatite

To correctly identify Blue Apatite (Apatite group (Fluorapatite)), 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 pale sky blue to deep indigo blue, sometimes with greenish or violet tints. Often exhibits pleochroism, showing different colors when viewed from different angles.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to sub-resinous.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth to slightly uneven fracture surfaces.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically forms hexagonal prisms, often with pyramidal terminations. Can also be found as tabular crystals, massive, or granular aggregates.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to indistinct on {0001} and {1010}.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in igneous rocks (especially pegmatites and carbonatites), metamorphic rocks (marbles, gneisses, schists), and hydrothermal veins. Also occurs in sedimentary phosphorite deposits.

Key Facts

Hardness

5 on the Mohs scale

Specific Gravity

3.16 - 3.22

Crystal System

Hexagonal

Color

Blue, often with greenish or violet tints; pleochroic

Luster

Vitreous to sub-resinous

Transparency

Transparent to translucent

Fracture

Conchoidal to uneven

Cleavage

Poor to indistinct on {0001} and {1010}

Composition

Calcium phosphate with fluorine (Ca5(PO4)3F)

Physical characteristics

• Crystal Habit: Hexagonal prismatic, tabular, massive, granular
• Cleavage Type: Poor to indistinct basal {0001} and prismatic {1010}
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle
• Luster Type: Vitreous to sub-resinous

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