Druzy Quartz on Hematite/Goethite
Quartz (Silicon Dioxide) and Goethite/Limonite · Mineral Specimen / Decorative Stone
Crystal System
Trigonal/Hexagonal system for the quartz; Orthorhombic for the matrix if goethite. Habit is druzy (micro-crystals) and botryoidal (globular matrix).
Mineral Group
Silicates (Tectosilicate) for the quartz; Oxides/Hydroxides for the dark matrix.
Chemical Formula
SiO2 (Quartz) with alpha-FeO(OH) (Goethite) or Fe2O3 (Hematite)
Formation Process
Hydrothermal and secondary enrichment; silica-rich fluids precipitate into cavities (vugs) within iron-rich host rocks at relatively low temperatures.
About This Crystal
The specimen features a layer of tiny, sparkling quartz crystals (druzy) coating a dark, chocolate-brown to black botryoidal matrix. The quartz is colorless to milky white with a vitreous luster, while the matrix is opaque with a sub-metallic to earthy luster.
Physical Characteristics
Color: clear/white on dark brown/black. Streak: White (quartz) / brownish-yellow (goethite). Specific Gravity: 2.65 (Quartz) to 4.3 (Goethite). Fluorescence: Generally none.
Optical Properties
Quartz is uniaxial positive with a refractive index of 1.544-1.553. The matrix is opaque. The overall specimen exhibits a sparkling 'sugar' effect due to light reflecting off multiple small crystal faces.
Hardness & Durability
Origin Region
Commonly found in Morocco (Oued Zem), Brazil, or USA (Arizona/Michigan). Forms in secondary oxidation zones of ore deposits.
Hardness & Durability
Quartz: 7.0 Mohs (hard); Matrix: 5.0-5.5 Mohs. Brittle tenacity; the druzy layer can be prone to shedding crystals if struck.
Care & Maintenance
Wash with warm soapy water and a soft brush. Avoid harsh chemicals that could react with the iron-oxide matrix. Store separately to prevent scratching other softer stones.
Rarity & Value
Relatively common. Value is determined by the aesthetics of the contrast between the white druse and dark matrix, and the overall coverage. Usually affordable for collectors ($10-$50 for small hand specimens).
Special Characteristics
Botryoidal (grape-like) growth habit of the iron ore matrix and the 'sparkle' or 'drusy' effect of the surface quartz crystals.
Lore & History
Historically, iron-rich stones were used as amulets for protection. In modern practices, quartz is considered an 'amplifier' of energy, while the dark matrix is associated with grounding and the root chakra. These are traditional folk beliefs.