Brazilian clear quartz cluster

Brazilian Clear Quartz Cluster (Mineralogical Description)

This specimen is a cluster of intergrown α-quartz crystals (SiO₂) exhibiting well-developed prismatic habits with multiple terminations. The crystals crystallized in the trigonal crystal system and display characteristic hexagonal prisms bounded by rhombohedral faces, reflecting stable quartz growth under silica-saturated conditions.

The absence of coloration indicates high chemical purity, with minimal trace-element substitution and a lack of radiation-induced or defect-related color centers. Optical transparency to translucency varies among individual crystals due to internal growth zoning, fluid inclusions, and minor lattice imperfections.

The cluster morphology formed through simultaneous nucleation and competitive growth of multiple crystals from a shared substrate within a hydrothermal vein or pegmatitic environment. Variations in crystal size, orientation, and termination geometry record localized differences in growth rates, fluid flow, and supersaturation during crystallization.

Brazil, particularly the Minas Gerais region, hosts extensive granitic and pegmatitic systems that provide optimal geological conditions for large-scale quartz crystallization, including prolonged availability of silica-rich fluids and stable thermal regimes.

Mineralogical properties:

• Chemical formula: SiO₂

• Polymorph: α-quartz

• Crystal system: Trigonal

• Space group: P3₁21 or P3₂21

• Hardness: 7 (Mohs)

• Cleavage: None

• Fracture: Conchoidal

• Luster: Vitreous

• Optical character: Uniaxial (+)

• Transparency: Transparent to translucent

This cluster represents a naturally formed aggregate of quartz crystals produced through hydrothermal crystallization over geologic timescales.