How to identify Fuchsite Quartzite

To correctly identify Fuchsite Quartzite (Fuchsite-bearing Quartzite), 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

   Varies from pale green to emerald green, often with a shimmering or sparkling effect due to fuchsite flakes.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (quartz) to pearly/silky (fuchsite). The overall rock often has a sub-vitreous to greasy luster with a distinct shimmer.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Granular, interlocking quartz grains. Can be fine-grained to medium-grained. The presence of mica flakes can give it a slightly schistose or foliated texture, though typically less pronounced than a true schist.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Quartz grains are anhedral to subhedral, interlocking. Fuchsite occurs as small, platy, anhedral flakes.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Quartz has no cleavage. Fuchsite exhibits perfect basal cleavage (001). The rock itself does not typically show a dominant cleavage plane, but may break along mica-rich layers if present.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Formed in regional metamorphic settings, often associated with ancient cratons and orogenic belts, where ultramafic rocks (source of chromium) or chromium-rich sediments were present prior to metamorphism.

Key Facts

Hardness

7 (Mohs scale, due to quartz dominance)

Specific Gravity

2.65 - 2.8 (variable depending on fuchsite content)

Crystal System

Quartz: Trigonal; Fuchsite: Monoclinic

Color

Green, due to chromium in fuchsite

Luster

Vitreous to pearly/silky

Transparency

Translucent to opaque

Fracture

Conchoidal to irregular (quartz), micaceous (fuchsite)

Cleavage

None for quartz; perfect basal for fuchsite

Composition

Predominantly SiO2 (quartz) with K(Al,Cr)2(AlSi3O10)(OH)2 (fuchsite)

Physical characteristics

• Crystal Habit: Massive, granular interlocking quartz with disseminated platy fuchsite flakes.
• Cleavage Type: Quartz: None; Fuchsite: Perfect basal on {001}.
• Fracture Type: Conchoidal to irregular (quartz), splintery (if mica-rich).
• Tenacity: Brittle.
• Luster Type: Vitreous (quartz) to pearly/silky (fuchsite).

Explore Fuchsite Quartzite