Agate
Quartz var. Chalcedony (Agate) · Semi-Precious Gemstone and Decorative Stone
Crystal System
Trigonal, microcrystalline habit forming in massive or nodular forms
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2
Formation Process
Hydrothermal and sedimentary processes where silica-rich groundwater deposits microcrystalline quartz in cavities
About This Crystal
Tumbled stone featuring a smooth, polished surface with translucent to opaque areas, displaying brownish-orange iron oxide inclusions and milky white banding patterns
Physical Characteristics
Color ranges from white and translucent grey to brown; white streak; no true cleavage; conchoidal fracture; specific gravity around 2.60 to 2.65; brittle tenacity
Optical Properties
Singly refractive aggregate appearance with microcrystalline birefringence, typically showing vitreous to waxy luster on polished surfaces
Hardness & Durability
Origin Region
Brazil, India, Madagascar, United States, and Uruguay, typically forming in cavities of volcanic rocks
Hardness & Durability
Mohs hardness of 6.5 to 7, making it durable and suitable for everyday jewelry use with good toughness
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid harsh chemicals and prolonged exposure to direct sunlight to prevent color fading
Rarity & Value
Common and widely available, with affordable pricing depending on size, pattern uniqueness, and polishing quality
Special Characteristics
Displays natural banding and mineral inclusions such as iron oxides creating picturesque dendritic or moss-like patterns
Lore & History
Historically used as an amulet for protection and grounding in ancient civilizations; associated with stability, balance, and emotional harmony in modern crystal lore