How to identify Apatite

To correctly identify Apatite (Apatite Group), 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

   Highly variable; commonly green, blue, yellow, brown, pink, purple, colorless, or white. Often translucent to transparent.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous to sub-resinous.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically crystalline, often forming well-formed hexagonal prisms. Can also be massive, granular, or botryoidal.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hexagonal system, typically forming prismatic crystals with pyramidal or pinacoidal terminations. Can also be tabular or acicular.

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 (e.g., granites, syenites, carbonatites, pegmatites), metamorphic rocks (e.g., marbles, gneisses, schists), and sedimentary rocks (e.g., phosphorites). Also occurs in hydrothermal veins.

Key Facts

Hardness

5 (Mohs scale)

Specific Gravity

3.1-3.2

Crystal System

Hexagonal

Color

Highly variable (green, blue, yellow, brown, pink, purple, colorless, white)

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 varying amounts of fluoride, chloride, and hydroxyl ions.

Physical characteristics

• Crystal Habit: Prismatic, tabular, acicular, massive, granular, botryoidal
• 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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