Simplify the following text for a Grade 5 native English-speaking person.
Original: The main economic activitiy is the copper mine of Mina Mexicana de Cobre , S.A de C. V , which employs most of the labor force ( 3,012 workers in 2000 ) .
Simplified: The main source of income is from the copper mine of Mina Mexicana de Cobre , S.A de C. V , which employs most of the labor force ( 3,012 workers in 2000 ) .