How to identify Pyrite

To correctly identify Pyrite (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 tarnished, iridescent sheen.

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 with smooth, often striated faces. Massive forms can be granular or botryoidal.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Commonly forms cubes, octahedra, and pyritohedra (a 12-faced form). Striations are often visible on cubic faces, running perpendicular to each other. Also found as massive, granular, radiating, or botryoidal aggregates.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to indistinct cleavage, typically exhibiting conchoidal to uneven fracture rather than true cleavage.

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 concretions in sedimentary rocks. Often associated with other sulfide minerals, quartz, and carbonates.

Key Facts

Hardness

6-6.5 (Mohs scale)

Specific Gravity

4.95-5.02 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 {100}

Composition

Iron sulfide (FeS2)

Physical characteristics

• Crystal Habit: Cubic, octahedral, pyritohedral, massive, granular, radiating, botryoidal. Often striated on cube faces.
• Cleavage Type: Poor/Indistinct
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle
• Luster Type: Metallic

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