Moss Agate
Quartz (Variety: Moss Agate) · Semi-Precious Gemstone / Decorative Stone
Crystal System
Trigonal (Hexagonal); typically occurs in microcrystalline massive habits or as nodules with no visible external crystal faces.
Mineral Group
Silicates (Tectosilicates); Quartz family, Chalcedony subgroup.
Chemical Formula
SiO2 (Silicon Dioxide) with inclusions of manganese or iron oxides
Formation Process
Hydrothermal; formed by the deposition of silica-rich groundwater in the cavities of volcanic rocks (vugs), where dendritic mineral impurities crystallize simultaneously.
About This Crystal
A translucent to semi-opaque chalcedony containing dark green, black, or reddish dendritic inclusions that resemble moss or foliage. It has a vitreous to waxy luster and shows a mottled appearance with white or clear quartz patchy areas.
Physical Characteristics
Color: Clear/White with green-to-black dendrites; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58–2.64; Fluorescence: Inert to weak green/yellow under UV.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: Up to 0.009; Pleochroism: None; Optical Character: Uniaxial positive; Lacks fire or dispersion.
Hardness & Durability
Origin Region
India (notable for high quality), Brazil, USA (Montana, Wyoming), and Uruguay. Found in weathered volcanic rocks and alluvial deposits.
Hardness & Durability
Mohs Hardness: 6.5–7; Toughness: Excellent (due to microcrystalline structure); Stability: Very stable, though high heat may alter the oxidation state of inclusions.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners if there are visible surface-reaching fractures. Store separately from harder stones like Sapphires to prevent scratches.
Rarity & Value
Common; Value is determined by the complexity and beauty of the 'moss' patterns. Generally affordable, often sold as tumbled stones or cabochons. Rarely treated, though some may be dyed.
Special Characteristics
Dendritic inclusions (pseudofossils) that create organic, plant-like patterns within the stone. Does not show chatoyancy or asterism.
Lore & History
Historically known as a 'gardener's stone' used to ensure a bountiful harvest. In metaphysical practices, it is associated with the Heart Chakra and believed to promote Emotional Balance and abundance.