How to identify Pyrite

To correctly identify Pyrite (Pyrite (Iron sulfide, 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

   Brass-yellow to golden-yellow, sometimes 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; massive or granular aggregates are also common. Crystal faces can be striated.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Cubic, octahedral, or pyritohedral crystals are characteristic. Penetration twins are also observed. Can also be massive, granular, or radiating.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to indistinct cleavage on {001}. It typically fractures conchoidally or unevenly rather than cleaving.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in igneous, metamorphic, and sedimentary rocks. Common in hydrothermal veins, contact metamorphic deposits, black shales, coal seams, and as an accessory mineral in various rock types. Often associated with other sulfide minerals.

Key Facts

Hardness

6-6.5 on the Mohs scale

Specific Gravity

4.95-5.03 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 {001}

Composition

Iron sulfide (FeS2)

Physical characteristics

• Crystal Habit: Cubic, octahedral, pyritohedral, massive, granular, radiating, stalactitic, concretions
• Cleavage Type: Poor/Indistinct
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle
• Luster Type: Metallic

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