How to identify Blue Quartz

To correctly identify Blue Quartz (Quartz (SiO2) with inclusions of fibrous magnesioriebeckite or crocidolite), 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

   Ranges from pale, milky blue to deep, vibrant blue. The color is often unevenly distributed or appears as a hazy blue due to the fibrous inclusions.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to greasy on fractured surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically massive, granular, or crystalline. May exhibit a slightly fibrous appearance internally due to inclusions.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hexagonal prisms terminated by rhombohedra, often twinned. Can also be found in massive, anhedral forms.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None (lacks true cleavage). Exhibits conchoidal fracture.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in metamorphic rocks (e.g., schists, gneisses), pegmatites, and hydrothermal veins. The presence of amphibole inclusions suggests formation in environments rich in iron, magnesium, and silica, often under regional or contact metamorphic conditions.

Key Facts

Hardness

7 (Mohs scale)

Specific Gravity

2.65 - 2.66

Crystal System

Trigonal

Color

Blue (due to inclusions)

Luster

Vitreous to greasy

Transparency

Translucent to opaque

Fracture

Conchoidal

Cleavage

None

Composition

SiO2 (Quartz) with inclusions of fibrous magnesioriebeckite or crocidolite (Na2(Mg3Fe2)Si8O22(OH)2 or Na2(Fe2+3Fe3+2)Si8O22(OH)2 respectively)

Physical characteristics

• Crystal Habit: Prismatic, massive, granular
• Cleavage Type: None
• Fracture Type: Conchoidal
• Tenacity: Brittle
• Luster Type: Vitreous to greasy

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