How to identify Smoky Quartz with Hematite

To correctly identify Smoky Quartz with Hematite (SiO2 with Fe2O3 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 gray, brown, or black with red, orange, or reddish-brown inclusions. The hematite inclusions can be dispersed, forming a uniform color, or concentrated in distinct patterns, phantoms, or layers.

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

   Smooth to slightly rough depending on the crystal habit and presence of surface inclusions.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically forms prismatic hexagonal crystals with pyramidal terminations. Can also be massive or granular. Hematite inclusions may form platy, granular, or acicular habits within the quartz.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None. Quartz exhibits conchoidal fracture.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal veins, pegmatites, granitic intrusions, and metamorphic rocks. Often found in cavities or vugs within these rock types where conditions allow for crystal growth.

Key Facts

Hardness

7 on the Mohs scale (for quartz). Hematite inclusions are softer (5-6.5), but the overall hardness is dominated by quartz.

Specific Gravity

2.65 g/cm³ (for quartz). Slightly higher if hematite inclusions are dense, up to ~2.7 g/cm³.

Crystal System

Trigonal (for quartz). Hematite is trigonal (rhombohedral).

Color

Smoky gray to black with red, orange, or reddish-brown inclusions.

Luster

Vitreous.

Transparency

Translucent to opaque.

Fracture

Conchoidal.

Cleavage

None.

Composition

Silicon dioxide (SiO2) with iron oxide (Fe2O3) inclusions.

Physical characteristics

• Crystal Habit: Prismatic hexagonal crystals with pyramidal terminations, massive, granular. Hematite inclusions can be platy, granular, or acicular.
• Cleavage Type: None.
• Fracture Type: Conchoidal.
• Tenacity: Brittle.
• Luster Type: Vitreous.

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