For seven years, dispossessed farmers have been fighting the Mexican government and the biggest mininig company in Mexico for a treasure nestling in the foot hills of the Sierra Madre. Now the farmers say the long battle will have come to an end. Mexicana de Cobre, a subsidiary of the mining conglomerate Grupo Mexico, last month lost an appeal to have its case heard before the Supreme Court, and has been ordered to return 1,500 hectares of exporpriated land to the farming community of Pilares de Nacozari. Unless there is a stay of execution, the land must be returned to its original owners soon.