Yes it certainly was, AIUI from teachings at school until 1972 and of course we all take that as gospel: That region of Africa had a massive copper belt across several countries making the biggest producer/exporter? of copper pre and post war.I don't recall Rhodesia ever being a major exporter of copper
Britain stopped buying their copper due to price rises in the 50's caused by the value of the pound against the dollar, we started using Ali as an alternative then, some 10 years before IDS declared independence mid 60's which everyone seems to cite as the cause.
AIUI the Ali cables were all imperial sizes (not checked this, please don't get upset) so nothing new made in ali in 70's (ish) for domestic sizes.