The following is a book citation:

In about 5000 B.C. [7000 years ago], someone in ancient Persia  discovered that fire from the glowing coals of an earthen furnace  would transform the green stone, malachite [Cu2CO3(OH)2], into the red metal, copper“.  [From, “Basic Concepts of Chemistry“, by Leo Malone, second edition, 1985, page 2].