How to identify Pyrite

To correctly identify Pyrite (Iron 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

   Pale brass-yellow to golden-yellow, often with a tarnished or iridescent surface.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Distinctive metallic luster, very bright and reflective.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically forms well-defined crystals; granular or massive aggregates are also common.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Cubes, octahedra, and pyritohedra are characteristic. Cube faces often show striations perpendicular to adjacent faces. Can also be massive, reniform, globular, or stalactitic.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to indistinct cleavage on {100}. Typically fractures conchoidally or unevenly.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in igneous rocks (as an accessory mineral), metamorphic rocks (e.g., schists, gneisses), and sedimentary rocks (especially black shales, coal seams, and limestones). Common in hydrothermal veins, contact metamorphic deposits, and as concretions.

Key Facts

Hardness

6-6.5 (Mohs scale)

Specific Gravity

4.95-5.10 g/cm³

Crystal System

Isometric (Cubic)

Color

Pale brass-yellow, golden-yellow

Luster

Metallic

Transparency

Opaque

Fracture

Conchoidal to uneven

Cleavage

Poor to indistinct on {100}

Composition

Iron sulfide (FeS2)

Physical characteristics

• Crystal Habit: Cubic, octahedral, pyritohedral, massive, granular, reniform, globular, stalactitic. Cube faces often striated.
• Cleavage Type: Poor/Indistinct
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle
• Luster Type: Metallic

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