Smoky Quartz (with Druzy coating)
Quartz var. Smoky Quartz · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; typically exhibits hexagonal prismatic habits with pyramidal terminations; this specimen shows a massive base with a microcrystalline druzy habit.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide with trace aluminum and natural irradiation)
Formation Process
Forms through hydrothermal crystallization or magmatic processes. The smoky color is caused by natural gamma irradiation of trace aluminum during or after the crystal growth in igneous and metamorphic environments.
About This Crystal
The specimen features a tan to light brownish-grey earthy matrix topped with a fine layer of druzy crystals. It exhibits a vitreous to dull luster depending on the facet, with varying transparency from translucent in the crystals to opaque in the host rock matrix.
Physical Characteristics
Color: Smoky brown/tan; Streak: White; Cleavage: None (poor); Fracture: Conchoidal to uneven; Specific Gravity: 2.65; Fluorescence: Generally inert, occasionally weak green under UV.
Optical Properties
Refractive Index: 1.544-1.553; Birefringence: 0.009; Pleochroism: Weak to moderate in darker stones; Diaphaneity: Translucent to Opaque.
Hardness & Durability
Origin Region
Globally abundant, notably from Brazil, USA (Colorado/Arkansas), Switzerland (Alps), and Madagascar; commonly found in pegmatites and metamorphic rocks.
Hardness & Durability
Mohs Hardness: 7; Toughness: Good (brittle but hard); Durable for jewelry but susceptible to surface abrasion if druzy crystals are exposed to high friction.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners if there are internal fractures; keep away from prolonged exposure to high heat and direct sunlight to prevent color fading.
Rarity & Value
Common; Value is determined by color saturation, crystal size, and the aesthetic appeal of the druzy coating. Untreated natural specimens are preferred over irradiated 'Black' quartz.
Special Characteristics
Features a 'Druzy' texture consisting of tiny micro-crystals that create a sparkling effect; some areas show potential for internal phantoms or minor rutilated inclusions.
Lore & History
Historically used in ancient Chinese culture for eyewear (sunglasses); traditionally associated in modern crystal lore with grounding energy, protection, and the root chakra.