Agate (Moss or Plume variety)
Quartz var. Agate (IMA-approved: Quartz) · Semi-Precious Gemstone / Decorative Stone
Crystal System
Trigonal/Hexagonal; microcrystalline (cryptocrystalline). Typically occurs in massive or nodular habits without visible crystal faces.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with inclusions of iron oxides (Fe2O3) and manganese oxides (MnO2)
Formation Process
Hydrothermal/Volcanic: Formed by the deposition of silica-rich groundwater in cavities of igneous rocks. Inclusions form via mineral precipitation during cooling.
About This Crystal
A polished oval cabochon displaying a translucent to opaque body. It features a complex 'mossy' or 'plume' pattern with dendritic inclusions in shades of rust-red, earthy gold, and blue-gray. The luster is vitreous (glass-like) when polished.
Physical Characteristics
Color: Multicolored (red, gold, blue, gray); Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58–2.64; Fluorescence: Variable, often inert or weak greenish-yellow.
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: ~0.009; No pleochroism; Primarily translucent with occasional opaque mineral inclusions.
Hardness & Durability
Origin Region
Commonly found in Brazil, India, Madagascar, and the USA (notably Oregon and Montana). Primarily forms in volcanic cavities (vugs).
Hardness & Durability
Mohs Hardness: 6.5–7; High toughness due to microcrystalline structure. Excellent wearability for all jewelry types.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid harsh chemicals and sudden temperature changes. Generally stable in sunlight but prolonged exposure can affect some iron-based colorants.
Rarity & Value
Common; value is determined by the complexity and beauty of the internal patterns. Highly detailed 'landscape' specimens command higher prices. Treatments like dyeing are common in some agates, though this specimen appears natural.
Special Characteristics
Dendritic/Plume Inclusions: The tree-like or cloud-like patterns are caused by manganese and iron oxides branching out as the silica gel hardened.
Lore & History
Historically used in amulets by ancient Greeks and Egyptians for protection and agricultural success. Traditionally associated with the Heart and Root chakras, it is believed to enhance emotional balance and gardener's 'green thumb'.