The unenriched mass has been designed and we are now ready for the consideration of surface enrichment in the following order.
In this connection Ransome defines primary ore as unenriched material that can be profitably mined.
late 14c., "to make wealthy," from Old French enrichir "enrich, enlarge," from en- "make, put in" (see en- (1)) + riche "rich" (see rich).
Figurative sense is from 1590s. Scientific sense of "to increase the abundance of a particular isotope in some material" is first attested 1945. Related: Enriched; enriching.