How to identify Pyrite

To correctly identify Pyrite (Pyrite (Iron sulfide)), 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 pale brass-yellow, sometimes with a slight greenish tint. Can tarnish to a duller, darker brassy color.

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 euhedral to subhedral crystals, granular aggregates, or massive forms. Crystal faces are often striated.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Commonly cubic, pyritohedral (12-faced pentagonal dodecahedron), or octahedral. Also found as massive, granular, reniform, or stalactitic aggregates. Penetration twins are common.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to indistinct on {001}. Typically fractures rather than cleaves.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in igneous, metamorphic, and sedimentary rocks. Common in hydrothermal veins, disseminated in igneous intrusions, in black shales, coal seams, and as concretions in sedimentary rocks. Also found in massive sulfide deposits.

Key Facts

Hardness

6-6.5 (Mohs scale)

Specific Gravity

4.95-5.10 g/cm³

Crystal System

Isometric (Cubic)

Color

Pale brass-yellow to 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, pyritohedral, octahedral, massive, granular, reniform, stalactitic. Striations often present on crystal faces.
• Cleavage Type: Poor/Indistinct
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle
• Luster Type: Metallic

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