Brant A. Gardner notes that, while no samples of metalworking has been found in Mesoamerica c. 1000 BC, linguistic evidence shows that terms for metal were known at that time.
Brant A. Gardner, Second Witness: Analytical and Contextual Commentary on the Book of Mormon, 6 vols. (Salt Lake City: Greg Kofford Books, 2007), 1:28n7
The timing of the development of metalworking in Mesoamerica is currently unknown. For many years the presumed earliest date for metalworking in Mesoamerica was 900 A.D., but several recent discoveries have pushed that time frame earlier. Linguistic evidence shows the terms for metal as early as 1000 B.C., although no samples have been found that approach that time-depth. . . .