North and South america have plenty of resources for smithing and mining. Native Americans also developed complicated agricultural societies and writing. Why didn't they take the next step and develop metal working?
You might also be interested in this previous thread which explains very well why there is no imperative for all societies to develop technology along similar lines: Out of all the Native American tribes, which were the most technologically advanced?.
hi! there's always room for more input, but FYI, you can get started on this section of the FAQ* (and I'm sure there are a few other posts kicking around... seems to be a related question came up a couple of weeks ago)
Metalworking in pre-Columbian America
*see the link on the sidebar or the wiki tab