Got a photo? Identify rocks instantly with the Rockby app
Open the appDescription
Smoky Quartz with Hematite is a variety of quartz characterized by its translucent to opaque smoky gray, brown, or black color, combined with distinct red, orange, or brown inclusions of hematite. The hematite inclusions can range from microscopic dustings that impart a uniform color to visible flakes, needles, or phantom-like structures within the quartz crystal. The smoky color is due to natural irradiation of aluminum impurities, while the red/orange/brown hues are from iron oxide (hematite) inclusions. The combination creates a visually striking mineral specimen.
How to Identify
- Color
- 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.
- Luster
- Vitreous (glassy) on crystal faces and fracture surfaces.
- Texture
- Smooth to slightly rough depending on the crystal habit and presence of surface inclusions.
- Crystal Form
- 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.
- Cleavage
- None. Quartz exhibits conchoidal fracture.
- Geological Environment
- 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.
Quick Check
- Color: Smoky gray/brown/black with red/orange/brown inclusions.
- Luster: Vitreous (glassy).
- Streak: White (for quartz), reddish-brown (for hematite if scratched directly, but difficult to obtain from inclusions within quartz).
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.
Formation
Smoky Quartz with Hematite forms primarily in hydrothermal veins, pegmatites, and igneous and metamorphic rocks. The quartz (SiO2) crystallizes from silica-rich fluids, often at elevated temperatures and pressures. The smoky coloration in quartz is generally attributed to natural irradiation of aluminum impurities within the crystal lattice, which creates color centers. The hematite (Fe2O3) inclusions occur when iron-rich fluids are present during the quartz's growth. Hematite can precipitate as fine particles, flakes, or even distinct crystals within the growing quartz, leading to red, orange, or brown coloration and sometimes a metallic sheen.
Usage
Primarily used as a gemstone, for ornamental purposes, and in mineral collections. Its unique appearance, combining the smoky translucence of quartz with the vibrant red or orange hues of hematite, makes it highly sought after. It is also used in metaphysical practices.
Age Distribution
Found in geological formations ranging from Precambrian to Cenozoic, depending on the host rock and hydrothermal activity.
Where to Find
Brazil
Minas Gerais is a significant source, known for large, well-formed crystals with varying degrees of smoky color and hematite inclusions.
Madagascar
Produces high-quality specimens, often with distinct red hematite phantoms or coatings.
United States
Various localities, including Arkansas, Colorado, and North Carolina, yield smoky quartz, sometimes with iron oxide staining or inclusions.
Switzerland
The Alps are famous for classic smoky quartz specimens, some of which contain iron oxide.
China
Several provinces produce quartz with hematite inclusions, often with vibrant red hues.
Finding Tips
Look for Hydrothermal Veins
Search in areas with exposed hydrothermal veins, especially those cutting through granitic or metamorphic rocks. These are prime locations for quartz crystallization.
Examine Pegmatites
Pegmatite dikes can host large quartz crystals, and the presence of iron-rich minerals in the surrounding rock or fluids can lead to hematite inclusions.
Check for Vugs and Pockets
Quartz crystals often grow in open spaces (vugs or pockets) within rocks. Look for these cavities, which may contain well-formed crystals.
Identify Iron Staining
The presence of reddish-brown iron staining on surrounding rocks can indicate the presence of iron oxides, which might be incorporated into quartz crystals.
Use a Magnifying Glass
Hematite inclusions can be very fine. A hand lens or magnifying glass will help distinguish them from other impurities or surface stains.
Similar Rocks
Smoky Quartz
SiO2
Also known as: Morion, Cairngorm
Red Quartz
SiO2 with various iron oxide inclusions
Also known as: Strawberry Quartz, Hematite Quartz (general term)
Amethyst
SiO2
Also known as: Purple Quartz
Scientific Classification
- Mineral Class
- Silicate (Tectosilicate)
- Group
- Quartz Group
- Crystal System
- Trigonal
- Chemical Formula
- SiO2 (with Fe2O3 inclusions)
- Composition
- Silicon dioxide with iron(III) oxide inclusions.
Explore Smoky Quartz with Hematite
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.