In TFA it is stated that before bronze (i.e. copper-tin alloy) copper was used for tools.

This is not true, because pure copper has always been too soft to be used in any tool. Pure copper was used for some purposes, but never for tools that had to be strong and hard, e.g. for knives.

Before bronze, for several millennia tools were made from alloys of copper and arsenic or antimony (3 metals, lead, copper and gold have been known for many millennia before other metals became known, like tin, silver and meteoritic iron). Neither of arsenic and antimony was known in pure form, so unlike the bronze made by mixing metallic copper with metallic tin, the copper-arsenic or copper-antimony alloys were made by mixing the sulfide minerals of copper and arsenic or antimony (which are all found together where sulfide minerals are mined), before smelting the metallic copper alloy from the minerals (which for sulfide minerals is done by first roasting the sulfides into oxides, to drive the sulfur away, then reducing the oxides with charcoal).