Smoky Quartz
Quartz var. Smoky Quartz (IMA-approved: Quartz) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically hexarhombohedral appearing as six-sided prisms. This specimen is carved and polished into a heart shape.
Mineral Group
Silicates (Subgroup: Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide) with Aluminum (Al3+) impurities and natural irradiation
Formation Process
Magmatic/Hydrothermal; forms in high-temperature environments. The dark color results from free silicon formed by natural gamma radiation of aluminum-bearing quartz.
About This Crystal
A heart-shaped polished stone exhibiting a translucent to near-opaque deep brown to grayish-black color. It shows a vitreous (glassy) luster with visible internal fractures and surface veining in a lighter tan-white shade.
Physical Characteristics
Color: Smoky brown to black; Streak: White; Cleavage: None (indistinct); Fracture: Conchoidal; Specific Gravity: 2.65; Fluorescence: Usually inert/none.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009 (Doubly refractive); Pleochroism: Weak to moderate in brown tones; Dispersion: 0.013.
Hardness & Durability
Origin Region
Brazil, Madagascar, USA (Colorado/Arkansas), Switzerland, and Scotland. Often found in granitic pegmatites and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good; Stability: Stable to light, but may fade if exposed to extreme heat (over 200-300°C). Excellent for all jewelry types.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic or steam cleaners if there are many internal fractures. Store away from heat and direct sunlight to prevent color loss.
Rarity & Value
Common; Value is determined by transparency and depth of color. Usually affordable, ranging from $1 to $10 per carat for polished stones. Treatments include irradiation of clear quartz to darken it.
Special Characteristics
Commonly contains internal veining, 'rainbows' from internal fractures, and sometimes inclusions like rutile needles or petroleum phantoms.
Lore & History
Historically used in China for the earliest sunglasses (12th century). Traditionally associated with the Root Chakra; believed in lore to provide grounding, protection from negative energy, and emotional stability.