Moss Agate (specifically Pigeon Blood or Plume Agate variety)
Chalcedony (cryptocrystalline Quartz) var. Agate · Semi-Precious Gemstone / Decorative Stone
Crystal System
Trigonal (Hexagonal system); typically occurs in microcrystalline massive or fibrous habits within nodules.
Mineral Group
Silicates; Tectosilicate (Quartz group)
Chemical Formula
SiO2 (Silicon Dioxide) with inclusions of Fe2O3 (Hematite) and various oxides
Formation Process
Hydrothermal/Sedimentary; forms via the deposition of silica from groundwater in cavities (vesicles) of volcanic lavas.
About This Crystal
An oval cabochon displaying a translucent bluish-grey chalcedony base with dense, plume-like or mossy inclusions of red, gold, and earthy brown. It features a vitreous (glassy) luster and high polish.
Physical Characteristics
Color: Multicolored (red, gold, grey); Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58–2.64; Fluorescence: Inert to weak green/yellow.
Optical Properties
Refractive Index: 1.530–1.543; Birefringence: up to 0.004; Optical character: Uniaxial positive; Diaphaneity: Translucent to opaque.
Hardness & Durability
Origin Region
Notable sources include Utah (Pigeon Blood), Oregon, and India. Historically found in volcanic rock cavities.
Hardness & Durability
Mohs Hardness: 6.5–7; Toughness: Excellent; Very durable for jewelry and daily wear with no cleavage planes to cause easy splitting.
Care & Maintenance
Clean with warm soapy water and a soft brush; safe for most jewelry use. Avoid harsh chemicals and sudden extreme temperature changes.
Rarity & Value
Common to Uncommon; Value is dictated by the complexity and beauty of the 'scenic' inclusions. Usually priced at $5–$50 per cabochon depending on size and patterns.
Special Characteristics
Contains 'plume' or 'moss' inclusions which are dendritic mineral growths (often iron or manganese) that mimic organic plant life or landscape scenes.
Lore & History
Historically used as an amulet for protection and success in agriculture. In lore, it is considered a stone of new beginnings and emotional balance, associated with the heart chakra.