I can't speak for the archaeologists and historians, but a fair representation of engineering talent agrees that the iron age probably did NOT replace the bronze age because iron was better than bronze. It was only because iron was easier to find and cheaper. (Like the basis for a lot of modern mfg/marketing decisions.)

Having once tried to drill a crack-stop hole in one of my kid's Zildjian cymbals, I decided to agree with the rest of the engineers.

It's a lot easier to make a hole in a piece of glass. It just melted the tips off of 3 HS tool steel drills. The cymbal was too hard to get a "bite" with any carbide drill I had so they just spun like they were on a ball bearing - and I couldn't really tell if the carbide might be almost as hard as the bronze. I got the hole through and smoothed up some only at the cost of wearing out a diamond-coated die grinding burr. (At least the burr was a little bit cheaper (not much) than a new cymbal.)

I think "Hard as the hubs of HELL" is the common term.

And adding insult to injury, the kid traded the whole trap set off for a bass guitar about three weeks later - - and tried to hit me up for a loan to buy an amp for it. (But he'd already been playing drums long enough that he probably didn't hear most of my reply.)

John