How to identify Pyrite

To correctly identify Pyrite (Iron disulfide (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

   Splendent metallic.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically crystalline, often forming distinct euhedral crystals. Can also be massive, granular, or botryoidal.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Cubic, octahedral, and pyritohedral forms are common. Faces are often striated. Also found as radiating aggregates or concretions.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor/indistinct on {001}. Typically exhibits conchoidal to uneven fracture rather than true cleavage.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in igneous rocks (as an accessory mineral, in magmatic sulfide deposits), metamorphic rocks (schists, gneisses), and sedimentary rocks (shales, coal seams, limestones, sandstones) where it forms under reducing conditions. Common in hydrothermal veins and contact metamorphic deposits.

Key Facts

Hardness

6-6.5 (Mohs scale)

Specific Gravity

4.95-5.03 g/cm³

Crystal System

Isometric (Cubic)

Color

Pale brass-yellow to golden-yellow

Luster

Metallic

Transparency

Opaque

Fracture

Conchoidal to uneven

Cleavage

Poor/indistinct on {001}

Composition

Iron disulfide (FeS2), containing 46.55% Fe and 53.45% S by weight.

Physical characteristics

• Crystal Habit: Cubic, octahedral, pyritohedral, massive, granular, radiating, botryoidal, stalactitic. Cube faces often striated.
• Cleavage Type: Poor/indistinct, typically fractures rather than cleaves.
• Fracture Type: Conchoidal to uneven.
• Tenacity: Brittle.
• Luster Type: Metallic, splendent.

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