OTHER NATURAL STONE
This can refer to Limestone, Travertine, Slate, Schist, and/or Onyx. Natural stones aren't limited to just these however.
Limestone and Travertine are made of the same materials and therefore have the same characteristics as Marble.
Slate is a type of “metamorphic” rock formed from plant material. It tends to have an oil content. Depending on where it comes from, the size of the slabs vary. Slate is a very stable material around acid but does not take a polish.
Schist refers to a type of Granite in that it usually has a quartz content that is readily visible (glitters) and tends to be a little more difficult to work because the Quartz is in layers that tend to slide against each other making it hard to keep it solid especially at the edges. It is a softer type of Granite,usually a darker color.
Onxy is an oddity of Silicon Dioxide (Chalcedony) similar to other harder stones but is smaller particles with lesser bonds to each other making it able to be sculpted. It can be said it is related to agate and usually translucent therefore perfect for backlighting.