Moss Agate
Chalcedony var. Moss Agate · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal (Hexagonal system); microcrystalline/cryptocrystalline habit, typically massive or as nodules
Mineral Group
Silicates (Tectosilicate), Oxide mineral group
Chemical Formula
SiO2 (Silicon Dioxide) with dendritic inclusions of Manganese or Iron oxides
Formation Process
Sedimentary/Hydrothermal; forms in cavities of volcanic rocks or as veins where silica-rich fluids deposit at low temperatures
About This Crystal
A translucent to semi-opaque variety of chalcedony containing dark, organic-looking dendritic inclusions that resemble moss or vegetation; colors include forest green, brownish-red, and grey-white with a waxy to vitreous luster
Physical Characteristics
Color: White, clear, or grey base with green/red inclusions; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58-2.64; Luster: Waxy to Vitreous; Diaphaneity: Translucent
Optical Properties
Refractive Index: 1.530–1.543; Birefringence: up to 0.004; Pleochroism: None; Dispersion: Low; Optical Character: Uniaxial positive
Hardness & Durability
Origin Region
Notable sources include India, Brazil, Uruguay, USA (Montana, Wyoming), and Central Europe
Hardness & Durability
Mohs Hardness: 6.5–7; Toughness: Very good due to cryptocrystalline structure; Stability: High, resistant to most household chemicals
Care & Maintenance
Clean with warm soapy water and a soft brush; safe for ultrasonic cleaners in most cases; avoid sudden temperature changes and harsh acids
Rarity & Value
Common to Uncommon; value is determined by the complexity and beauty of the 'landscape' or moss-like patterns and translucency of the chalcedony base
Special Characteristics
Features dendritic inclusions (pseudo-fossils) that form branching patterns; some specimens may show slight fluorescence under UV light depending on trace elements
Lore & History
Known historically as the 'Gardener's Stone' for its association with agriculture and nature; used in ancient amulets for protection and abundance; traditionally linked to the Heart Chakra and grounding energies