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rare earth oxides

June 2005 (approx.)

Detailed Description

These rare-earth oxides are used as tracers to determine which parts of a watershed are eroding. Clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium, and gadolinium. Image Number D1115-1. Photo by Peggy Greb, USDA-ARS.