Why is marble good for the rock tombstone?

Marble actually is NOT a good stone for tombstones (also called monuments), granite is much better.

The reason marble is so abundant in older sections of cemeteries is the fact that marble is a very soft, porous stone. It was easier to carve letters and designs into marble with a hammer and chisel as opposed to granite.

When air compressors came around, pneumatic chisels came into the picture and granite became the stone of choice, due to its density and durability over time.