Ancient granite pottery proves someone in the distant past had access to a very high level of technology. We've only recently (last few decades) had enough technology ourselves to have the nessesary context to even recognize the fingerprint of technology in their stone work.
Either,
1. The Egyptions were way more technical capable than we give them credit. I doubt it.
2. They were recycling another older and more advanced societies materials.
To think we could be looking at pottery that is over 10 thousand years old blows my mind.
Any material other than stone would have eroded away thousands of years ago. And the only reason these stone vases would have survived the last 5 thousand years is because the Egyptions purposefully buried and preserved them in a area with no rainfall.