Moss Agate
Quartz var. Chalcedony · Semi-Precious Gemstone / Decorative Stone
Crystal System
Trigonal (specifically Microcrystalline); this specimen is cut into a polished hexagonal pillar or obelisk habit.
Mineral Group
Silicates (Tectosilicate group)
Chemical Formula
SiO2 (Silicon Dioxide) with dendritic inclusions of Manganese or Iron silicates
Formation Process
Hydrothermal / Sedimentary; formed from the deposition of silica-rich fluids in rock cavities at relatively low temperatures, where mineral oxides grow in dendritic patterns.
About This Crystal
A translucent to opaque chalcedony featuring moss-like green filaments or dendritic patterns. The specimen shown is a polished obelisk with a vitreous to waxy luster, displaying variegated shades of forest green against a light gray-white translucent background.
Physical Characteristics
Color: Green, white, gray; Streak: White; Cleavage: None; Fracture: Conchoidal to uneven; Specific Gravity: 2.58-2.64; Luster: Vitreous to waxy; Fluorescence: Usually inert but can show dull green.
Optical Properties
Refractive Index: 1.530-1.543; Birefringence: Up to 0.004; Diaphaneity: Translucent to opaque; No distinct pleochroism or dispersion.
Hardness & Durability
Origin Region
Major deposits include India, Brazil, Uruguay, and the United States (notably Montana). Forms in volcanic cavities and sedimentary rock.
Hardness & Durability
Mohs Hardness: 6.5 to 7. Toughness: High (due to microcrystalline structure). Stability: Stable against light and most chemicals; sensitive to hydrofluoric acid.
Care & Maintenance
Safe to clean with warm soapy water and a soft brush. Avoid ultrasonic or steam cleaners if there are visible surface fractures. Store separately to prevent scratching softer stones.
Rarity & Value
Common; Value is driven by the complexity and beauty of the 'moss' patterns. Generally inexpensive and widely available in the lapidary market.
Special Characteristics
Dendritic inclusions: The 'moss' is not organic material, but rather branching mineral inclusions (manganese or iron) resembling plants. May features small druzy pockets.
Lore & History
Historically known as the 'Gardener's Stone' and used by farmers in the 18th century to ensure healthy crops. In crystal lore, it is associated with the Heart Chakra and believed to promote groundedness, abundance, and a connection to nature.