How to identify Smoky Quartz with Inclusions

To correctly identify Smoky Quartz with Inclusions (SiO2 (Quartz) with various mineral 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

   Translucent to opaque smoky brown, gray, or black, with the color of inclusions varying widely (e.g., golden for rutile, black for tourmaline, green for chlorite, red for hematite).

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) on crystal faces and fracture surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically smooth on crystal faces, conchoidal fracture surfaces. Inclusions may create internal textures visible through the quartz.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Hexagonal prisms terminated by rhombohedra. Often found as euhedral to subhedral crystals. Inclusions are typically anhedral to euhedral within the quartz host.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None. Quartz lacks cleavage.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Pegmatites, hydrothermal veins, granitic rocks, metamorphic rocks, and alpine-type fissures. The presence of radioactive elements in the surrounding rock is crucial for the smoky coloration. Inclusions reflect the specific mineralogy of the formation environment.

Key Facts

Hardness

7 on the Mohs scale (for quartz). Inclusions may have different hardnesses but are protected by the quartz.

Specific Gravity

2.65 g/cm³ (for quartz). May vary slightly depending on the density and abundance of inclusions.

Crystal System

Trigonal.

Color

Smoky brown, gray, or black, with inclusions of various colors (e.g., golden, black, green, red).

Luster

Vitreous.

Transparency

Transparent to translucent.

Fracture

Conchoidal.

Cleavage

None.

Composition

Silicon dioxide (SiO2) with aluminum impurities and various encapsulated mineral inclusions.

Physical characteristics

• Crystal Habit: Prismatic, often forming hexagonal prisms terminated by rhombohedral faces. Can also be massive or granular. Inclusions can be acicular, fibrous, platy, or granular.
• Cleavage Type: Absent.
• Fracture Type: Conchoidal.
• Tenacity: Brittle.
• Luster Type: Vitreous.

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