Clear Quartz (Rock Crystal)
Quartz (IMA-approved name); variety: Rock Crystal · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; Trapezohedral class. Habit: Prismatic with hexagonal cross-sections, often terminated by two sets of rhombohedra. In this specimen, it appears as a druzy/crystalline cluster.
Mineral Group
Silicates; Subgroup: Tectosilicates (Framework Silicates)
Chemical Formula
SiO2 (Silicon Dioxide); May contain trace impurities of Al, Fe, Ti, or Li
Formation Process
Primarily Hydrothermal (precipitating from silica-rich hot water in veins or cavities) or Igneous (crystallizing from cooling magma in pegmatites). Formed under a wide range of T-P conditions.
About This Crystal
Transparent to translucent colorless crystals. Shows vitreous (glassy) luster on crystal faces. This specimen displays a crystalline/druzy habit with numerous small interlocking points and some reddish-brown iron oxide staining on the matrix.
Physical Characteristics
Color: Colorless/White. Streak: White. Cleavage: Indistinct/None. Fracture: Conchoidal. Specific Gravity: 2.65. Tenacity: Brittle. Fluorescence: Typically inert under UV light, though some specimens may show faint green or yellow.
Optical Properties
Refractive Index: 1.544–1.553. Birefringence: 0.009 (Uniaxial positive). Pleochroism: None. Dispersion: 0.013. Optical Phenomena: Occasional iris effect from internal fractures (as seen in the prismatic flash on the right).
Hardness & Durability
Origin Region
Globally abundant. Notable sources include Brazil (Minas Gerais), USA (Arkansas), Madagascar, and the Alps (Switzerland/France). Typically found in pegmatites, hydrothermal veins, and metamorphic rocks.
Hardness & Durability
Mohs Hardness: 7. Toughness: Fair to Good. Stability: Highly stable; resistant to acids (except Hydrofluoric) and heat, though thermal shock can cause cracking.
Care & Maintenance
Safe to clean with warm soapy water, ultrasonic cleaners, and steam. Store separately to avoid scratching softer stones. Avoid extreme temperature shocks.
Rarity & Value
Common. Value is determined by clarity, size, and crystal perfection. Large, well-formed terminated points or clusters command higher prices. Common treatments: Irradiation (to darken) or Dyeing (for crackle quartz).
Special Characteristics
Piezoelectric and Pyroelectric properties. This specific specimen shows 'Rainbow' iris effect (diffraction) on a central cleavage plane and possible iron-rich 'phantom' or surface inclusions.
Lore & History
Historically used in 'scrying' spheres and ancient jewelry. Cultures like the Ancient Greeks believed it was permanently frozen ice ('krystallos'). In metaphysical traditions, it is known as the 'Master Healer,' associated with the Crown Chakra and amplification of energy.