How to identify Quartzite

To correctly identify Quartzite (Metamorphic rock, primarily composed of quartz), 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

   Typically white or light gray, but can be pink, red, yellow, green, or blue due to impurities. Pure quartzite is white.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to greasy on freshly broken surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Granular, sugary, interlocking crystalline texture. Original clastic grains are obliterated.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Anhedral, interlocking quartz grains, typically equigranular.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   No true cleavage. Exhibits conchoidal to splintery fracture, breaking across the quartz grains.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Formed in regions of intense heat and pressure, such as convergent plate boundaries (orogenic belts) or areas affected by deep burial and contact metamorphism. Often found in ancient mountain ranges and cratonic shields.

Key Facts

Hardness

7 on the Mohs scale

Specific Gravity

2.65 g/cm³ (for pure quartz)

Crystal System

Trigonal (for quartz mineral)

Color

White, gray, pink, red, yellow, green, blue

Luster

Vitreous to greasy

Transparency

Translucent to opaque

Fracture

Conchoidal to splintery

Cleavage

None (breaks across grains)

Composition

Primarily quartz (SiO2), typically >90-95%.

Physical characteristics

• Crystal Habit: Massive, granular, interlocking anhedral grains.
• Cleavage Type: None. Quartz itself has no cleavage.
• Fracture Type: Conchoidal to splintery, breaking through the quartz grains.
• Tenacity: Brittle
• Luster Type: Vitreous (glassy) to greasy

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