Moss Agate
Quartz var. Agate (variety of Chalcedony) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal (specifically microcrystalline or cryptocrystalline); habits include massive, nodular, and polished point forms as seen in the specimen.
Mineral Group
Silicates (Subgroup: Tectosilicates)
Chemical Formula
SiO2 (Silicon Dioxide) with dendritic inclusions of Ferrous Silicate, Chlorite, or Manganese and Iron Oxides
Formation Process
Hydrothermal/Sedimentary; forms when silica-rich fluids permeate cavities in volcanic rock. The green 'moss' inclusions are dendritic minerals that crystallize before the host silica solidifies.
About This Crystal
Translucent to semi-opaque chalcedony containing green, branching dendritic inclusions. The specimen is polished into a hexagonal point, showing a waxy to vitreous luster and characteristic cloud-like patterns.
Physical Characteristics
Color: Colorless/milky white with green inclusions. Streak: White. Cleavage: None. Fracture: Conchoidal. Specific Gravity: 2.58–2.64. Diaphaneity: Translucent to opaque.
Optical Properties
Refractive Index: 1.530–1.543. Birefringence: Up to 0.004. It is an aggregate of doubly refractive microscopic crystals. It does not exhibit pleochroism.
Hardness & Durability
Origin Region
Prominently sourced from India, Brazil, Uruguay, and the United States (Montana, Oregon). Usually found in weathered volcanic residues.
Hardness & Durability
Mohs Hardness: 6.5–7. Toughness: High (due to cryptocrystalline structure). Good stability and wearability for jewelry.
Care & Maintenance
Safe to clean with warm soapy water. Avoid harsh chemicals and sudden temperature shocks. While generally stable, some dyed varieties can fade, though natural moss agate is lightfast.
Rarity & Value
Common and affordable. Value is determined by the complexity of the dendritic patterns and the translucency of the chalcedony base. Rare patterns can command higher prices.
Special Characteristics
Dendritic inclusions resembling moss or plants; may show minor fluorescence under UV light depending on trace mineral content in the inclusions.
Lore & History
Historically used as a talisman by agricultural societies to ensure bountiful harvests. In modern crystal healing, it is associated with the Heart Chakra and believed to promote grounding and emotional balance.