How to identify Rutilated Quartz

To correctly identify Rutilated Quartz (SiO2 with TiO2 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 can be colorless, white, smoky, or rarely amethystine. Rutile inclusions are typically golden-yellow, reddish-brown, coppery, or sometimes black.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

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

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth, conchoidal fracture for the quartz. The rutile inclusions are acicular (needle-like) and can be felt if exposed on a broken surface, though typically encased.

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) crystals within the quartz.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Quartz: None. Rutile: Distinct on {110} and {100}.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, pegmatites, and regionally metamorphosed rocks. Often found in association with other minerals typical of these environments, such as feldspar, mica, and other titanium-bearing minerals.

Key Facts

Hardness

7 on Mohs scale (for quartz host); 6-6.5 (for rutile inclusions).

Specific Gravity

2.65 (for quartz host); 4.2-4.3 (for rutile inclusions). The overall specific gravity of rutilated quartz will be slightly higher than pure quartz depending on the density of rutile inclusions.

Crystal System

Trigonal (for quartz host); Tetragonal (for rutile inclusions).

Color

Colorless, white, smoky, or rarely amethystine quartz with golden, reddish-brown, coppery, or black rutile needles.

Luster

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

Transparency

Transparent to translucent.

Fracture

Conchoidal (for quartz).

Cleavage

None (for quartz); distinct on {110} and {100} (for rutile).

Composition

SiO2 (quartz) with TiO2 (rutile) inclusions.

Physical characteristics

• Crystal Habit: Quartz: Prismatic, often terminated. Rutile inclusions: Acicular (needle-like), often epitaxial.
• Cleavage Type: Quartz: Absent. Rutile: Distinct.
• Fracture Type: Conchoidal (for quartz).
• Tenacity: Brittle.
• Luster Type: Vitreous (quartz), Adamantine to Sub-metallic (rutile).

Explore Rutilated Quartz