How to identify Turquoise with Pyrite

To correctly identify Turquoise with Pyrite (Turquoise (CuAl6(PO4)4(OH)8·4H2O) with Pyrite (FeS2)), 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

   Turquoise: Sky-blue, blue-green, apple-green. Pyrite: Pale brass-yellow, metallic.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Turquoise: Waxy to subvitreous. Pyrite: Metallic.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Turquoise: Cryptocrystalline, massive, often with a fine-grained texture. Pyrite: Crystalline, often as distinct cubes, octahedra, or irregular grains.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Turquoise: Typically massive, reniform, botryoidal, or stalactitic; rarely as small, tabular crystals. Pyrite: Commonly forms cubes, pyritohedra, octahedra, or massive aggregates.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Turquoise: Poor to indistinct on {001}. Pyrite: Indistinct on {001} and {110}.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Secondary enrichment zones in arid climates, often associated with porphyry copper deposits, where supergene alteration processes have occurred. Pyrite is a common accessory mineral in these environments, forming under reducing conditions.

Key Facts

Hardness

Turquoise: 5-6 (Mohs). Pyrite: 6-6.5 (Mohs).

Specific Gravity

Turquoise: 2.60-2.90. Pyrite: 4.95-5.10.

Crystal System

Turquoise: Triclinic. Pyrite: Isometric.

Color

Turquoise: Sky-blue, blue-green, apple-green. Pyrite: Pale brass-yellow.

Luster

Turquoise: Waxy to subvitreous. Pyrite: Metallic.

Transparency

Turquoise: Opaque. Pyrite: Opaque.

Fracture

Turquoise: Conchoidal to uneven. Pyrite: Conchoidal to uneven.

Cleavage

Turquoise: Poor to indistinct on {001}. Pyrite: Indistinct on {001} and {110}.

Composition

Turquoise: Hydrous copper aluminum phosphate (CuAl6(PO4)4(OH)8·4H2O). Pyrite: Iron disulfide (FeS2).

Physical characteristics

• Crystal Habit: Turquoise: Massive, cryptocrystalline, reniform, botryoidal. Pyrite: Cubic, pyritohedral, octahedral, massive.
• Cleavage Type: Turquoise: Poor/Indistinct. Pyrite: Indistinct.
• Fracture Type: Conchoidal to uneven for both minerals.
• Tenacity: Turquoise: Brittle. Pyrite: Brittle.
• Luster Type: Turquoise: Waxy to subvitreous. Pyrite: Metallic.

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