How to identify Chalcopyrite with Quartz

To correctly identify Chalcopyrite with Quartz (Chalcopyrite (CuFeS2) with 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

   Chalcopyrite: Brassy yellow, often tarnishing to iridescent blues, purples, and reds. Quartz: Colorless, white, gray, or various other colors depending on impurities.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Chalcopyrite: Metallic. Quartz: Vitreous (glassy) to greasy.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Chalcopyrite: Granular, massive, or crystalline. Quartz: Crystalline, massive, or granular.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Chalcopyrite: Tetragonal, often forming disphenoids, but commonly massive. Quartz: Hexagonal, forming prismatic crystals with pyramidal terminations, or massive.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Chalcopyrite: Poor, indistinct cleavage in one direction {011}. Quartz: None (conchoidal fracture).

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, porphyry copper deposits, volcanogenic massive sulfide (VMS) deposits, skarn deposits, and disseminated in igneous and metamorphic rocks.

Key Facts

Hardness

Chalcopyrite: 3.5-4 (Mohs); Quartz: 7 (Mohs)

Specific Gravity

Chalcopyrite: 4.1-4.3; Quartz: 2.65

Crystal System

Chalcopyrite: Tetragonal; Quartz: Trigonal (often referred to as hexagonal in habit)

Color

Chalcopyrite: Brassy yellow, often tarnished iridescent; Quartz: Colorless, white, gray, or various hues

Luster

Chalcopyrite: Metallic; Quartz: Vitreous to greasy

Transparency

Chalcopyrite: Opaque; Quartz: Transparent to translucent

Fracture

Chalcopyrite: Uneven to conchoidal; Quartz: Conchoidal

Cleavage

Chalcopyrite: Poor, indistinct {011}; Quartz: None

Composition

Chalcopyrite: Copper iron sulfide (CuFeS2); Quartz: Silicon dioxide (SiO2)

Physical characteristics

• Crystal Habit: Chalcopyrite: Commonly massive, granular, or in disphenoidal crystals. Quartz: Prismatic crystals with pyramidal terminations, massive, granular, or cryptocrystalline.
• Cleavage Type: Chalcopyrite: Poor, indistinct. Quartz: Absent.
• Fracture Type: Chalcopyrite: Uneven to conchoidal. Quartz: Conchoidal.
• Tenacity: Chalcopyrite: Brittle. Quartz: Brittle.
• Luster Type: Chalcopyrite: Metallic. Quartz: Vitreous to greasy.

Explore Chalcopyrite with Quartz