How to identify Pyrite with Quartz

To correctly identify Pyrite with Quartz (Pyrite (FeS2) and Quartz (SiO2)), 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

   Pyrite: Brassy yellow, metallic. Quartz: Colorless, white, gray, purple, pink, brown, black (depending on variety and impurities).

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Pyrite: Metallic. Quartz: Vitreous to greasy.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Pyrite: Crystalline, often euhedral to subhedral crystals (cubes, octahedra, pyritohedra). Quartz: Crystalline, massive, granular, or cryptocrystalline.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Pyrite: Commonly cubes, octahedra, pyritohedra, or combinations, often striated. Quartz: Hexagonal prisms with pyramidal terminations, massive, or anhedral grains.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Pyrite: Indistinct to poor on {001}. Quartz: None (conchoidal fracture).

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, metamorphic rocks, sedimentary rocks (as concretions or disseminated grains), igneous rocks (as accessory minerals).

Key Facts

Hardness

Pyrite: 6-6.5 (Mohs). Quartz: 7 (Mohs).

Specific Gravity

Pyrite: 4.95-5.10. Quartz: 2.65.

Crystal System

Pyrite: Isometric. Quartz: Trigonal.

Color

Pyrite: Pale brass-yellow. Quartz: Colorless, white, or various hues due to impurities.

Luster

Pyrite: Metallic. Quartz: Vitreous to greasy.

Transparency

Pyrite: Opaque. Quartz: Transparent to translucent.

Fracture

Pyrite: Uneven to conchoidal. Quartz: Conchoidal.

Cleavage

Pyrite: Indistinct to poor. Quartz: None.

Composition

Pyrite: Iron disulfide (FeS2). Quartz: Silicon dioxide (SiO2).

Physical characteristics

• Crystal Habit: Pyrite: Cubes, octahedra, pyritohedra, massive, granular, radiating. Quartz: Prismatic, massive, granular, cryptocrystalline.
• Cleavage Type: Pyrite: Indistinct to poor, parting on {110}. Quartz: None.
• Fracture Type: Pyrite: Uneven to conchoidal. Quartz: Conchoidal.
• Tenacity: Pyrite: Brittle. Quartz: Brittle.
• Luster Type: Pyrite: Metallic. Quartz: Vitreous to greasy.

Explore Pyrite with Quartz