Red corundum is ruby.
Al2O3 is corundum, red corundum is ruby, blue is sapphire
SiO2 is silicon dioxide, usually associated with silicates like quartz, purple quartz is amethyst.
So I am not a gemologist, but I would say the stones are mostly ruby but mixed with other minerals, those are impurities, trace elements or inclusions like titanium oxide, ferrous oxide, chromium oxide, indicated by the various concentrations. I am not an expert but it seems to me it is more than half ruby. I do not know if industry standards are applicable. I do know for a stone to be considered an agate, it has to be 50 percent agate. By that standard, it is a ruby.