Moss Agate
Quartz var. Moss Agate (Chalcedony) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal (Microcrystalline/Cryptocrystalline); typically found in massive or nodular habits rather than distinct crystals.
Mineral Group
Silicates (Tectosilicate)
Chemical Formula
SiO2 (Silicon Dioxide) with inclusions of manganese or iron oxides/silicates
Formation Process
Hydrothermal; formed by the deposition of silica from groundwater into cavities of igneous rocks at relatively low temperatures.
About This Crystal
A translucent to semi-opaque chalcedony containing dark, dendritic inclusions that resemble moss or foliage. The body color is typically milky white or gray-blue, while the inclusions are dark green, black, or reddish-brown with a vitreous to waxy luster.
Physical Characteristics
Color: Multicolored (White/Grey with Green/Black/Red); Streak: White; Cleavage: None; Fracture: Conchoidal to uneven; Specific Gravity: 2.58–2.64; Tenacity: Brittle; Fluorescence: Generally inert or dull yellowish-white.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: Up to 0.009; Pleochroism: None; Optical character: Uniaxial positive; Generally exhibits a translucent quality.
Hardness & Durability
Origin Region
India, Brazil, USA (Montana and Wyoming), Uruguay, and Central Europe; occurs in cavities of weathered volcanic rocks.
Hardness & Durability
Mohs Hardness: 6.5–7; Toughness: Very Good (durable due to microcrystalline structure); Stability: Stable but can be affected by hydrofluoric acid and extreme heat.
Care & Maintenance
Safe to clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaners if the stone has surface-reaching fractures. Store away from harder gems like Topaz or Sapphire to avoid scratching.
Rarity & Value
Common; Value is determined by the complexity and beauty of the 'moss' patterns. Generally inexpensive and sold as tumbled stones, cabochons, or decorative carvings.
Special Characteristics
Dendritic inclusions: The moss-like patterns are not organic but are mineral growths (dendrites) formed by manganese or iron oxides that crystallized during the stone's formation.
Lore & History
Historically known as a stone of agriculture and gardening; used in ancient amulets to ensure a bountiful harvest. In modern metaphysical practices, it is associated with the Heart Chakra and believed to promote groundedness and emotional balance.