Of, relating to, or found in alluvium: alluvial soil; alluvial gold. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "alluvial" in a sentence
"Diamonds occur in alluvial lands mostly open and comparatively level, as in India, the Brazil and the Cape."
"Estimates of "prehistoric" and early historic diamond production suggest that 50 to 100,000 carats per year were found, mostly in alluvial deposits in river gravels."
"Sapphires are found in alluvial soil near rocks and embedded in gneiss."