Granite and Marble too ordinary?? Try Onyx. Considered an exotic material, Onyx is unique, beautiful, translucent so it can be backlit, but it has a number of downsides. Onyx slabs are softer and more prone to chips, scratches and damage. Onyx is expensive, many times the cost of even expensive granites and marble. There is a lot of movement in the slabs so predicting what the top may look like is more difficult.
Below are links to three articles with more on Onyx Countertops.
Source: How Do Onyx Countertops Hold Up
Source: Onyx Countertops