gemstone
Gem Gravel
Alluvial Gem Gravel (Mixed silicate minerals)
AI-generated identification · may be incorrectComposed of small, rounded to sub-angular pebbles of various hardnesses (mostly Mohs 7 for quartz/beryl). Exhibits vitreous to dull luster with natural alluvial rounding.
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Physical properties
Composed of small, rounded to sub-angular pebbles of various hardnesses (mostly Mohs 7 for quartz/beryl). Exhibits vitreous to dull luster with natural alluvial rounding.
Formation & geological history
Formed via weathering and fluvial transport of pegmatites and metamorphic rocks, concentrated in riverbeds in regions like Madagascar.
Uses & applications
Sourced primarily for gem-hunting, lapidary work, and extracting precious gemstones like tourmaline, sapphire, and quartz.
Geological facts
Madagascar is world-renowned for rich alluvial gem gravels found in river valleys, often yielding rare minerals.
Field identification & locations
Found in alluvial deposits and river placers; identify by panning or sorting through coarse sand and gravel beds.
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