Very very good point Sal, definitely! Yes actually there is a French chemist named Davidovits who pioneered that idea and he and others founded an entire new branch of chemistry called geopolymers based on it. The idea makes a lot of sense, and at the very least, these silicate based polymers are very useful to modern industry. Basically, they are chemical stone that can be cast like concrete, but, has the strength of chemical stone, such as limestone.
Here are some websites on this:
Really, this makes a lot more sense to me than ancient people having some sort of secret energy beam and gravity beam technology. It fits in more with what we have discovered as their pre industrial technologies go. The idea is that some of them discovered that certain mixes of clay based materials can set into hard stone structures, at normal temperatures and pressures, and these can be used for construction blocks and other things.
There are diorite vases and objects and as you may know diorite is very hard, (http://rocks.comparenature.com/en/prope ... model-13-6
) with the 6-7 on the Mohs Scale, diamond being 10 and sapphire being about 9 to 9.5. They claim steel knife blades, depending on the steel alloy, are in the 5-7 range.
If these people were pre industrial in other aspects, as they appear to have been, but, learned to cast stone like we cast concretes and cements, it makes sense how they could make monoliths, vases, and pyramids out of very hard stone blocks that normal hand carving and chiseling would not allow. They could use their standard hand tools to shape the soft material and then let it harden to stone-hardness.
I also like how you point out that like today, you can have primitive and advanced societies existing side by side.
Regarding knives, as steel alloys become more and more advanced, and ceramic compounds also become more advanced, it is almost as if we are entering a "New Stone Age".
https://www.geopolymer.org/faq/replicat ... stonework/