Smoky Quartz (with possible Granite Matrix)
Quartz var. Smoky (Silicon Dioxide) · Collector Mineral / Semi-Precious Gemstone
Crystal System
Trigonal; typically hexangonal prisms with pyramidal terminations. This specimen appears as an irregular, massive, or broken crystal fragment.
Mineral Group
Silicates; Subgroup: Tectosilicate
Chemical Formula
SiO2 (Trace aluminum and natural irradiation provide the smoky color)
Formation Process
Primarily Magmatic or Hydrothermal. Common in pegmatites and igneous rocks like granite where natural radiation from surrounding minerals affects the crystal structure.
About This Crystal
An opaque to translucent mineral specimen featuring a mottled appearance of dark grey to black smoky quartz intermixed with lighter, whitish minerals (likely feldspar or mica). The surface appears rough, dull to vitreous in spots, with a jagged, irregular habit.
Physical Characteristics
Color: Smoky brown to black and white/grey; Streak: White; Cleavage: None (poor); Fracture: Conchoidal to uneven; Specific Gravity: 2.65; Fluorescence: Usually inert.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Weakly pleochroic in darker specimens; Singly refractive usually, but shows double refraction under polariscope.
Hardness & Durability
Origin Region
Globally abundant; notable sources include the Swiss Alps, Brazil, Madagascar, and the Pikes Peak region of Colorado, USA.
Hardness & Durability
Mohs Hardness: 7.0; Toughness: Good (brittle); Highly durable and resistant to most household chemicals, making it excellent for jewelry.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid prolonged exposure to intense direct sunlight, which can occasionally cause color fading in specific smoky quartz varieties.
Rarity & Value
Common; Value is generally low for rough specimens, with price increases based on clarity, size, and the presence of rare inclusions like rutile.
Special Characteristics
Often exhibits 'phantom' growth layers or rutilated inclusions; the smoky color is a result of free silicon formed by radiation-induced coloration of aluminum impurities.
Lore & History
Historically used in 12th-century China to make the first 'sunglasses' (flat panes of smoky quartz). Metaphysically associated with the Root Chakra and traditionally used as a 'grounding' stone to transform negative energy.