KD-600 brochure says:
ARCB consists of limestone particles, glass particles and limestone bonded unsaturated polyester resin.
KD-500 brochure says:
"Construction of Cabinet is Anti-Resonance Compression Base (ARCB). This Massive ARCB is Compression Molded from Lime-Stone Particles, Unsaturated Polyester Resin, Lime-Stone and Glass Powder" Directly from the poop sheet for the table.
Concrete per wiki or some such place:
Is a composite construction material composed primarily of aggregate, cement, and water.
Corian according to the web:
Is composed of acrylic polymer and alumina trihydrate (ATH).
Not that I have any idea what alimina trihydrate is but I can copy and paste so there is what we have.
Not that any of that is going to help clean the base you have. I have tried some of the finer finishing compounds without success. But I wasn't as concerned and stopped after trying that (plast-x from meguiar's or something like that).