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Quartz crystal with chlorite inclusions is a variety of quartz (silicon dioxide, SiO2) that contains visible inclusions of chlorite group minerals. These inclusions typically impart a green, greenish-yellow, or brownish-green color to parts of or the entire quartz crystal. The chlorite can appear as fine dustings, mossy aggregates, distinct layers (forming 'phantoms'), or even well-formed crystals within the quartz. The transparency of the quartz can range from clear to milky, and the inclusions can be dense or sparse.
How to Identify
- Color
- Clear to milky white quartz with green, greenish-yellow, or brownish-green inclusions. The green color is characteristic of chlorite.
- Luster
- Vitreous (glassy) for the quartz, dull to pearly for the chlorite inclusions.
- Texture
- Smooth, hard surface of quartz, with potential for rougher or fibrous textures where chlorite is densely included or exposed.
- Crystal Form
- Typically hexagonal prisms terminated by rhombohedral faces for the quartz. Chlorite inclusions may follow the growth patterns of the quartz, forming 'phantoms', or appear as scattered flakes/aggregates.
- Cleavage
- Quartz has no true cleavage, exhibiting conchoidal fracture. Chlorite has perfect basal cleavage (one direction).
- Geological Environment
- Hydrothermal veins, metamorphic rocks (schists, gneisses), igneous rocks (granites, pegmatites), often associated with low-grade metamorphism or alteration zones.
Key Facts
- Hardness: 7 (Mohs scale for quartz); 2-2.5 (Mohs scale for chlorite)
- Specific Gravity: 2.65 (for quartz); 2.6-3.3 (for chlorite, varies with composition)
- Crystal System: Trigonal (for quartz); Monoclinic (for chlorite)
- Color: Colorless to white (quartz) with green, greenish-yellow, or brownish-green inclusions (chlorite).
- Luster: Vitreous (quartz); dull to pearly (chlorite)
- Transparency: Transparent to translucent (quartz); opaque to translucent (chlorite inclusions)
- Fracture: Conchoidal (quartz); uneven to splintery (chlorite)
- Cleavage: None (quartz); Perfect basal (001) (chlorite)
- Composition: SiO2 (Quartz) with various chlorite group minerals, typically (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6
Quick Check
- Color: Clear to milky with green, greenish-yellow, or brownish-green inclusions.
- Luster: Vitreous (glassy) for quartz, dull to pearly for inclusions.
- Streak: White (for quartz); green to greenish-white (for chlorite, if powdered separately, which is difficult within quartz).
Physical Characteristics
- Crystal Habit: Quartz: Prismatic, often terminated with rhombohedral faces, massive, granular. Chlorite inclusions: Disseminated flakes, fibrous, mossy, or layered within quartz.
- Cleavage Type: Quartz: None. Chlorite: Perfect in one direction (basal).
- Fracture Type: Quartz: Conchoidal. Chlorite: Uneven to splintery.
- Tenacity: Quartz: Brittle. Chlorite: Flexible, inelastic.
- Luster Type: Quartz: Vitreous. Chlorite: Dull to pearly.
Formation
Quartz crystals with chlorite inclusions form when chlorite minerals are present during the growth of quartz. This typically occurs in hydrothermal veins, metamorphic rocks (e.g., schists, gneisses), or igneous rocks (e.g., granites, pegmatites) where chlorite is a common alteration product or primary mineral. The chlorite particles are trapped within the growing quartz lattice, often forming distinct layers or phantoms as the quartz crystal grows in stages.
Usage
Primarily used as a collector's mineral specimen, in lapidary for cabochons and carvings, and in metaphysical practices. It has no significant industrial applications beyond that of clear quartz, as the inclusions are generally considered aesthetic rather than functional.
Age Distribution
Can form in geological environments ranging from Precambrian to Cenozoic, depending on the host rock and metamorphic/hydrothermal activity.
Where to Find
Brazil
Known for producing large, high-quality quartz crystals with various inclusions, including chlorite, often forming distinct phantom layers.
Himalayan Mountains (e.g., Pakistan, Nepal)
Source of clear quartz with fine, often mossy or dusty chlorite inclusions, sometimes referred to as 'Himalayan Green Quartz'.
United States (e.g., Arkansas, North Carolina)
Various localities produce quartz with chlorite, particularly in metamorphic terrains or hydrothermal deposits.
Switzerland (Alps)
Alpine clefts are famous for producing pristine quartz crystals, some of which contain chlorite inclusions.
Finding Tips
Look for Green Hues
The most obvious indicator is the presence of green coloration within otherwise clear or milky quartz. The green can range from pale to dark, and its distribution can be uniform, patchy, or layered.
Examine Crystal Growth Patterns
Chlorite inclusions often highlight growth stages, forming 'phantom' crystals within the larger quartz crystal. Look for these internal outlines.
Check for Associated Minerals
Chlorite-included quartz is often found in environments with other metamorphic or hydrothermal minerals. Identifying the geological context can aid in discovery.
Hardness Test
The quartz itself will be hard (Mohs 7). While the chlorite inclusions are softer (Mohs 2-2.5), they are protected by the quartz, so a scratch test on the quartz surface will yield a hardness of 7.
Similar Rocks
Epidote in Quartz
SiO2 with Epidote
Also known as: Epidote Quartz
Actinolite in Quartz
SiO2 with Actinolite
Also known as: Actinolite Quartz
Seraphinite
Mg5Al(AlSi3O10)(OH)8
Also known as: Clinochlore
Scientific Classification
- Mineral Class
- Silicate (Quartz: Tectosilicate; Chlorite: Phyllosilicate)
- Group
- Quartz Group (for SiO2); Chlorite Group (for inclusions)
- Crystal System
- Trigonal (Quartz); Monoclinic (Chlorite)
- Chemical Formula
- SiO2 (Quartz) + (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6 (General Chlorite Formula)
- Composition
- Silicon dioxide with hydrous magnesium iron aluminum silicate inclusions.
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