Marble slabs and Onyxes are the most luxurious natural stones due to their distinct veins and swirls in bold colors. Their calcite based composition makes them softer than granite and therefore more vulnerable to scratches, etching and staining. Even with a heavy duty sealer, inappropriate use of cleaning agents can cause a chemical attack, permanently etching the surface of the countertops. For these reasons, we do not recommend either stone for kitchen countertops. For those who do choose one of these options, however, we are your marble suppliers.