> But with a stone tool made out of something such as granite, isn't it correct that the only requirement is that the tool is not unduly compressed/crushed for

> But with a stone tool made out of something such as granite, isn't it correct that the only requirement is that the tool is not unduly compressed/crushed for it to survive 10s of thousands to millions of years? Stone tools were made mostly from flint due to the way it cleaves with sharp edges. Granite and other stone tools weren't used until the neolithic as ground stones. In order to survive for that long, stone tools mostly just had to avoid moving water. Anything that fell into a river or ocean would be worn away quickly (like beach glass). Unfortunately, until the end of the last glacial period (~12,000 years ago), the sea level was much lower than it is today and most human habitation has long since been flooded by the melting glaciers. Underwater archaeology is a new field that's growing in importance but it's slow going and the ocean is much more dynamic that dry land.