I dont see anywhere that the Inca could smelt platinum. Everything Ive seen suggests they used native, ie metallic, platinum which they then mixed with gold in an amalgam. A couple of sources explicitly said they could NOT reach the temperatures necessary to melt platinum.
- What about Steel? Leaving aside the fact that one thousand steel swords and a few crossbows plus a handful of harkbuses are a death wish when pitted against one hundred thousand bronze maces, bone-tipped spears and pebble-shooting wool slings, the Inka could learn of ferrous metallurgy from Spanish POWs. They were the first to smelt platinum, which has a far higher melting point.
Do you have sources that show they did?