How to identify Pyrite

To correctly identify 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

   Pale brass-yellow to golden-yellow, often tarnishing to a darker, duller 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 well-defined crystals; granular or massive aggregates also occur. Crystal faces are often striated.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Commonly forms cubes, octahedra, and pyritohedra. Penetration twins are also observed. Striations on cubic faces are perpendicular to each other.

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 ore deposits.

Key Facts

Hardness

6-6.5 on the 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 {001}

Composition

Iron sulfide (FeS2)

Physical characteristics

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

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