Agate
Quartz var. Agate · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal, microcrystalline crypto-crystalline habit forming banded or nodular masses
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2
Formation Process
Hydrothermal and secondary deposition, typically forming in cavities of volcanic rocks (vugs and vesicles) via silica-rich groundwater precipitation
About This Crystal
Small, tumbled or polished smooth stone featuring translucent yellowish-brown chalcedony body transitioning into a patterned cap with distinct brown and reddish spots or dendritic inclusions resembling mini-landscapes
Physical Characteristics
Color varies from translucent off-white and pale yellow to reddish-brown spots; white streak; no cleavage; conchoidal fracture; specific gravity around 2.60 to 2.65; brittle tenacity; vitreous to waxy luster
Optical Properties
Refractive index ranges from 1.544 to 1.553; doubly refractive (uniaxial positive); generally non-pleochroic; displays translucency with banded or inclusion patterns
Hardness & Durability
Origin Region
Worldwide, with notable deposits in Brazil, Madagascar, Uruguay, India, and the USA
Hardness & Durability
Mohs hardness of 6.5 to 7; good toughness and durability making it highly suitable for jewelry wear and everyday handling
Care & Maintenance
Safe to clean with warm soapy water and soft brush; avoid harsh ultrasonic cleaners, sudden thermal shocks, and prolonged harsh chemical exposure
Rarity & Value
Common and widely accessible; value depends heavily on unique patterning, vivid colors, and intricate inclusions, making custom-patterned specimens desirable for collectors
Special Characteristics
Banded microcrystalline structure, distinct spotty inclusions, and micro-chalcedony translucency
Lore & History
Historically used as an amulet for protection, grounding, and balancing emotional energy; associated traditionally with stabilizing the root and sacral chakras