sedimentary
Banded Agate
Silicon Dioxide (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Variegated lavender, grey, and red bands; Luster: Waxy to vitreous; Crystal Structure: Trigonal (Cryptocrystalline); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Variegated lavender, grey, and red bands
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Variegated lavender, grey, and red bands; Luster: Waxy to vitreous; Crystal Structure: Trigonal (Cryptocrystalline); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.64
Formation & geological history
Formed in cavities of volcanic rocks or ancient sedimentary formations where silica-rich groundwater deposited layers of microcrystalline quartz over thousands of years.
Uses & applications
Used primarily for lapidary arts, jewelry (cabochons), ornamental carvings, and as a popular collector's specimen due to its unique banding.
Geological facts
Agate banding is often the result of rhythmic crystallization which produces alternating layers of different colors or porosities. No two agates are exactly alike.
Field identification & locations
Identify in the field by its translucent properties when held to light and its smooth, waxy fracture surface. Commonly found in riverbeds, gravel pits, and volcanic regions.
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