stones are classed as ceramic!
cement is classed as ceramic!
concrete is classed as ceramic!

for your information, concrete and cement arnet the same thing apparently (I thought they were). Cement is a mixture of lime, silica and alumina, which sets when mixed with water. Concrete is sand and stones held together by cement.

Stone is also classed as (natural) ceramic. limestone, sandstone, granite (typically used in building foundations and construction) are all natural ceramics!

So thank you Jodie and Ross, for showing me that rock is actually ceramic. I did think it might have been, but its nice to have it confirmed by both people and a very clever engineering book (Engineering Materials 2 by Jones and Ashby).

I was getting worried there for a while.