How to identify Red Quartz

To correctly identify Red Quartz (Quartz (SiO2) with iron oxide inclusions), 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 pinkish-red to deep brick-red, reddish-brown, or orange-red. The color is due to iron oxide inclusions.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) on crystal faces and fresh fractures; can be duller if heavily included or weathered.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically crystalline, ranging from macrocrystalline (visible crystals) to cryptocrystalline (microscopic crystals, though this would be more chalcedony/jasper). Inclusions may give a granular or speckled appearance.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hexagonal prisms terminated by rhombohedra (often forming a pseudo-hexagonal bipyramid). Can also be massive, granular, or drusy.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None (lacks cleavage). Exhibits conchoidal fracture.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, pegmatites, igneous rocks (e.g., granites, rhyolites), metamorphic rocks (e.g., quartzites), and sedimentary environments where silica and iron oxides are present.

Key Facts

Hardness

7 on the Mohs scale

Specific Gravity

2.65 g/cm³ (for pure quartz; may be slightly higher with dense iron oxide inclusions)

Crystal System

Trigonal

Color

Red, reddish-brown, orange-red, pinkish-red

Luster

Vitreous

Transparency

Transparent to translucent to opaque, depending on the density and type of inclusions.

Fracture

Conchoidal

Cleavage

None

Composition

Silicon dioxide (SiO2) with inclusions of iron oxides (primarily hematite, Fe2O3, and goethite, FeO(OH)).

Physical characteristics

• Crystal Habit: Prismatic, massive, granular, drusy, cryptocrystalline (as chalcedony/jasper).
• Cleavage Type: None (lacks cleavage).
• Fracture Type: Conchoidal (shell-like, curved fractures).
• Tenacity: Brittle.
• Luster Type: Vitreous (glassy) to sometimes greasy or dull on fracture surfaces.

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