Agate
Quartz var. Agate · Semi-Precious Gemstone and Decorative Stone
Crystal System
Trigonal, microcrystalline (Chalcedony); typically forms in rounded nodules, amygdules, or massive veins.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2
Formation Process
Hydrothermal and sedimentary; forms by the deposition of silica from groundwater or hydrothermal solutions in cavities of volcanic or sedimentary rocks, often in concentric layers.
About This Crystal
A polished, rounded tumble stone exhibiting translucent to opaque areas with warm honey-yellow, brown, and milky white coloration. It displays characteristic curved banding and internal inclusions typical of cavity-filling microcrystalline quartz.
Physical Characteristics
Color ranges from white to brown and yellow; streak is white; cleavage is absent; fracture is conchoidal to uneven; specific gravity is approximately 2.60 to 2.65; tenacity is brittle; lacks significant magnetism or native fluorescence.
Optical Properties
Refractive index ranges from 1.544 to 1.553; doubly refractive (uniaxial positive microcrystalline); exhibits no strong pleochroism due to microcrystalline aggregate structure.
Hardness & Durability
Origin Region
Found globally; notable sources include Brazil, India, Madagascar, Uruguay, and the United States (Lake Superior region, Oregon).
Hardness & Durability
Mohs hardness of 6.5 to 7; good toughness and durability; highly stable against standard wear, making it excellent for daily-wear jewelry.
Care & Maintenance
Safe to clean with warm soapy water; avoid harsh acids or prolonged exposure to extreme heat; store separately from softer materials to prevent scratching.
Rarity & Value
Common and widely accessible; value is primarily determined by pattern distinctness, color richness, size, and polish quality; treatments such as dyeing are common for commercial material, though this specimen appears naturally colored.
Special Characteristics
Displays natural concentric banding, translucent depth, and localized brownish inclusions resembling small internal phantoms or fortification patterns.
Lore & History
Historically used by ancient civilizations including the Greeks and Egyptians for amulets, seals, and ornamentation. In modern metaphysical practices, agate is traditionally associated with grounding, emotional balance, stability, and strengthening the root chakra.