Moss Agate
Chalcedony (cryptocrystalline Quartz) with inclusions of Ferro-magnesium minerals · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal (specifically microcrystalline/cryptocrystalline); Habit is usually massive, botryoidal, or as nodules.
Mineral Group
Silicate class, Tectosilicate subgroup (Quartz group)
Chemical Formula
SiO2 (Silicon Dioxide) with inclusions often containing Iron, Manganese, or Chlorite
Formation Process
Hydrothermal formation where silica-rich fluids deposit in volcanic rock cavities or fissures at relatively low temperatures.
About This Crystal
A translucent to semi-opaque white or grey chalcedony featuring dendritic, moss-like inclusions of green, brown, or black mineral oxides. It has a waxy to vitreous luster and a smooth, uneven surface texture in its raw form.
Physical Characteristics
Color: White/grey base with green/brown inclusions; Streak: White; Cleavage: None; Fracture: Conchoidal to uneven; Specific Gravity: 2.58–2.64; Fluorescence: Often inert but can show dull yellow-green under LWUV.
Optical Properties
Refractive Index: 1.530–1.540; Birefringence: Up to 0.004; Pleochroism: None; Optical character: Aggregate; Phenomena: Dendritic inclusions creating a moss-like visual effect.
Hardness & Durability
Origin Region
India, Brazil, USA (Montana), Uruguay, and Central Europe; typically found in volcanic basalt cavities.
Hardness & Durability
Mohs Hardness: 6.5 to 7; Toughness: Very good (durable due to microcrystalline structure); Stability: Generally high, stable under most conditions.
Care & Maintenance
Wash with warm soapy water and a soft brush. Avoid harsh chemicals and ultrasonic cleaners if the stone has significant surface-reaching fractures. Store separately to prevent scratching softer stones.
Rarity & Value
Common; Value is determined by the complexity and beauty of the internal patterns (dendrites) and the transparency of the host chalcedony. Generally affordable.
Special Characteristics
Distinctive dendritic patterns resembling plant life (pseudofossils), though they are entirely inorganic mineral growths (typically chlorite or manganese oxides).
Lore & History
Historically used as an amulet for gardeners and agriculture. In lore, it is considered a stone of 'new beginnings' and abundance, traditionally associated with the Heart Chakra and stabilization of physical energy.