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Quartz with Hematite is a variety of quartz that contains inclusions of hematite, giving it a range of colors from yellow, orange, and red to reddish-brown. The intensity and distribution of the color depend on the concentration and form of the hematite. The quartz itself is typically transparent to translucent, and the hematite inclusions can appear as fine dustings, distinct phantoms, or dense masses. Specular hematite inclusions can give a metallic sparkle.
How to Identify
- Color
- Ranges from pale yellow, orange, and red to reddish-brown. Can also exhibit a metallic sheen if specular hematite is present.
- Luster
- Vitreous (glassy) for the quartz, often with a sub-metallic to metallic luster from hematite inclusions.
- Texture
- Typically crystalline, often with well-formed quartz crystal faces. Inclusions can be finely disseminated or form distinct patterns.
- Crystal Form
- Hexagonal prisms terminated by rhombohedra (for quartz). Hematite inclusions can be anhedral to euhedral within the quartz.
- Cleavage
- None (for quartz). Hematite has no distinct cleavage.
- Geological Environment
- Hydrothermal veins, pegmatites, metamorphic rocks, and sedimentary environments where iron-rich fluids or sediments interact with silica-rich solutions.
Key Facts
- Hardness: 7 on Mohs scale (for quartz component)
- Specific Gravity: 2.65 - 2.69 (for quartz, slightly higher with dense hematite inclusions)
- Crystal System: Trigonal (for quartz)
- Color: Yellow, orange, red, reddish-brown
- Luster: Vitreous to sub-metallic/metallic
- Transparency: Transparent to translucent
- Fracture: Conchoidal (for quartz)
- Cleavage: None
- Composition: Silicon dioxide (SiO2) with iron oxide (Fe2O3) inclusions
Quick Check
- Color: Yellow, orange, red, reddish-brown
- Luster: Vitreous to sub-metallic/metallic
- Streak: White (for quartz), reddish-brown (if hematite is rubbed directly)
Physical Characteristics
- Crystal Habit: Prismatic, often terminated by rhombohedra; massive, granular. Hematite inclusions can be disseminated, botryoidal, or platy.
- Cleavage Type: Absent
- Fracture Type: Conchoidal
- Tenacity: Brittle
- Luster Type: Vitreous (quartz), sub-metallic to metallic (hematite)
Formation
Quartz with Hematite forms when silicon dioxide (SiO2) crystallizes in the presence of iron oxides, primarily hematite (Fe2O3). The hematite can be present as microscopic inclusions within the quartz crystal lattice, as coatings on the crystal faces, or as macroscopic intergrowths. This typically occurs in hydrothermal veins, pegmatites, and sedimentary environments where iron-rich fluids or sediments are present during quartz growth. The iron oxides can be introduced during the initial crystallization of quartz or later through secondary alteration processes.
Usage
Primarily used as an ornamental stone, for lapidary purposes (cabochons, spheres, carvings), and in jewelry. Due to its aesthetic appeal, it is popular among mineral collectors. It does not have significant industrial uses beyond its quartz component, which is ubiquitous.
Age Distribution
Varies widely depending on the geological setting, from Precambrian to Cenozoic.
Where to Find
Brazil
Minas Gerais is a significant source, producing large, well-formed crystals with vibrant hematite inclusions.
Madagascar
Known for producing high-quality hematoid quartz, often with distinct red and orange hues.
United States
Various localities, including Arizona and Arkansas, yield quartz with iron oxide staining and inclusions.
South Africa
Produces specimens with strong red coloration due to hematite.
China
Several regions produce quartz with hematite, often with interesting phantom formations.
Finding Tips
Look for Hydrothermal Veins
Explore areas with quartz veins, especially those associated with iron-rich host rocks or mineralized zones.
Examine Sedimentary Formations
Check for quartz crystals in iron-rich sedimentary environments, such as those near banded iron formations or red beds.
Identify Iron Staining
Look for reddish-brown staining on rocks and in soil, which can indicate the presence of iron oxides and potentially hematoid quartz.
Check for Crystal Habits
Search for characteristic hexagonal quartz crystals, which may contain visible hematite inclusions or coatings.
Similar Rocks
Jasper
Cryptocrystalline Quartz (SiO2) with iron oxide impurities
Also known as: Red Jasper, Yellow Jasper
Carnelian
Chalcedony (SiO2) with iron oxide impurities
Also known as: Cornelian
Iron-stained Quartz
Quartz (SiO2) with external iron oxide/hydroxide coatings
Also known as: Limonite-stained Quartz
Scientific Classification
- Mineral Class
- Silicate (Quartz), Oxide (Hematite)
- Group
- Tectosilicate (Quartz), Hematite Group (Hematite)
- Crystal System
- Trigonal (Quartz), Hexagonal (Hematite)
- Chemical Formula
- SiO2 (Quartz) + Fe2O3 (Hematite)
- Composition
- Silicon dioxide with iron(III) oxide
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