How to identify Pyrite

To correctly identify 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

   Brassy-yellow to golden-yellow, sometimes with a brownish tarnish. The color is consistent and uniform.

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, often cubic, octahedral, or pyritohedral. Can also be massive, granular, or radiating.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Cubic crystals are most common, often with striations on the faces. Octahedral and pyritohedral forms are also frequent. Can also occur as radiating aggregates or massive forms.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to indistinct cleavage on {100}. It typically fractures conchoidally or unevenly rather than cleaving.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in a wide variety of geological settings: hydrothermal veins, sedimentary rocks (especially black shales, coal), metamorphic rocks, and as an accessory mineral in some igneous rocks. Often associated with other sulfide minerals, quartz, calcite, and various ore minerals.

Key Facts

Hardness

6-6.5 (Mohs scale)

Specific Gravity

4.95-5.03 g/cm³

Crystal System

Isometric

Color

Brassy-yellow, golden-yellow

Luster

Metallic

Transparency

Opaque

Fracture

Conchoidal to uneven

Cleavage

Poor to indistinct on {100}

Composition

Iron disulfide (FeS2)

Physical characteristics

• Crystal Habit: Cubic, octahedral, pyritohedral, massive, granular, radiating, stalactitic
• Cleavage Type: Poor/Indistinct {100}
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle
• Luster Type: Metallic

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