How to identify Rutilated Quartz

To correctly identify Rutilated Quartz (Quartz with Rutile 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

   Host quartz is typically colorless (clear), smoky, or milky white. Rutile inclusions are golden yellow, reddish-brown, coppery, or black.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) for the quartz host; sub-metallic to adamantine for the rutile inclusions.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth, conchoidal fracture for quartz. The rutile needles are typically smooth and metallic-looking within the quartz.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Quartz typically forms hexagonal prisms terminated by rhombohedra. Rutile inclusions are acicular (needle-like) or fibrous, often oriented parallel to the c-axis of the quartz or in radiating patterns.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Quartz has no true cleavage, exhibiting conchoidal fracture. Rutile has distinct cleavage on {110} and {100}, but this is rarely observable within the quartz host.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, pegmatites, and metamorphic rocks. Often found in areas with significant tectonic activity and fluid circulation.

Key Facts

Hardness

7 on the Mohs scale for quartz; 6-6.5 for rutile.

Specific Gravity

2.65 g/cm³ for quartz; 4.2-4.3 g/cm³ for rutile (overall specific gravity of Rutilated Quartz will be slightly higher than pure quartz depending on rutile density).

Crystal System

Trigonal for quartz; Tetragonal for rutile.

Color

Colorless, smoky, or milky quartz with golden, reddish, coppery, or black rutile inclusions.

Luster

Vitreous for quartz; sub-metallic to adamantine for rutile.

Transparency

Transparent to translucent for quartz; opaque for rutile inclusions.

Fracture

Conchoidal for quartz.

Cleavage

None for quartz; distinct on {110} and {100} for rutile (not typically observed in inclusions).

Composition

Silicon dioxide (SiO2) for quartz; Titanium dioxide (TiO2) for rutile.

Physical characteristics

• Crystal Habit: Quartz: Prismatic, often terminated by rhombohedra. Rutile inclusions: Acicular (needle-like), fibrous, sometimes radiating or stellate.
• Cleavage Type: Quartz: None. Rutile: Distinct on {110} and {100}.
• Fracture Type: Conchoidal for quartz.
• Tenacity: Brittle.
• Luster Type: Vitreous for quartz; sub-metallic to adamantine for rutile.

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