
sedimentary
Nile Agate
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs. Color: translucent brown, honey, and greyish-green with visible concentric banding. Luster: waxy to vitreous. Structure: Cryptocrystalline quartz. Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Luster
- waxy to vitreous
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Physical properties
Hardness: 6.5-7 Mohs. Color: translucent brown, honey, and greyish-green with visible concentric banding. Luster: waxy to vitreous. Structure: Cryptocrystalline quartz. Cleavage: None (conchoidal fracture).
Formation & geological history
Formed by the deposition of silica from groundwater within cavities (vesicles) of igneous rocks or sedimentary voids. These specimens are often weathered out and transported by fluvial processes, common in the Cenozoic sediments of the Nile Basin.
Uses & applications
Used primarily for jewelry (cabochons, beads), decorative lapidary work, and as a collectible gemstone.
Geological facts
Nile agates are known for their beautiful, intricate banding and are often found as water-worn pebbles in the deserts of Sudan and Egypt. They have been used for thousands of years in the making of amulets and beads in ancient Saharan cultures.
Field identification & locations
Identify by looking for waxy luster, translucency when held to light, and characteristic 'eye' or linear banding. Highly consistent with the geology of North-Eastern Sudan (17.6°N, 34.0°E), which features vast Cretaceous to Tertiary sedimentary deposits and gravel plains containing silica-rich nodules.
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