Smoky Quartz (with Limonite/Goethite associations)
Quartz var. Smoky Quartz · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal system; typically occurs in hexagonal prismatic habits with pyramidal terminations; often found here as a massive or granular vein filling.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with Aluminum (Al) trace elements and natural irradiation
Formation Process
Hydrothermal or Igneous; forms via the cooling of silica-rich fluids in veins or cavities. The brown/yellow staining suggests subsequent exposure to iron-rich fluids (Limonite).
About This Crystal
The specimen features a translucent to opaque quartz core with visible smoky/yellowish hues. It is surrounded by a dark, irony crust (likely Goethite or Limonite). Luster is vitreous on fresh surfaces and dull/earthy on the matrix.
Physical Characteristics
Color: Grayish-brown to yellow; Streak: White; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65; Fluorescence: Usually inert under UV light; Magnetism: None.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: 0.009; Uniaxial (+); No notable pleochroism or dispersion in this rough state.
Hardness & Durability
Origin Region
Global occurrences; notably found in Brazil, Madagascar, and the Alps. This specimen shows signs of hydrothermal vein formation in a ferruginous host rock.
Hardness & Durability
Mohs Hardness: 7. Toughness: Fair to Good. Highly durable for jewelry, though the matrix/crust is much softer (Mohs 5-5.5) and brittle.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners if the matrix is porous. Store away from direct sunlight to prevent potential color fading over centuries.
Rarity & Value
Common; Value is determined by clarity and size. Massive vein quartz like this has primarily collector or decorative value rather than high gem value.
Special Characteristics
Features iron-oxide staining and potential internal 'phantom' growth layers. The surface shows some micro-druzy features in the vugs.
Lore & History
Historically used in Scotland as 'Cairngorm' stones for jewelry and weapons. Traditionally associated with grounding, protection, and the root chakra in modern mineral lore.