2006, Edwin Black, chapter 2, in Internal Combustion[1]:
One typical Grecian kiln engorged one thousand muleloads of juniper wood in a single burn. Fifty such kilns would devour six thousand metric tons of trees and brush annually.
Infrequently used in Commonwealth countries (including Britain) in contexts where confusion might arise between the metric ton and the traditional English tons of 2000 or 2240 pounds, in which case tonne is preferred.