European standard NBN EN 1936.

This standard expresses the mass of the natural stone in kilograms per cubic metre (kg/m3). This cubic metre is made up of stone and pores (air).
The result gives an indication of the level of compactness of the natural stone. The higher the result, the more compact (and therefore less porous) the stone.

Limestone	1500-2800 kg/m³
Marble	2600-2800 kg/m³
Granite	2500-3000 kg/m³
Slate	2650-3000 kg/m³

As might be expected, the granites and slates are far more compact than the limestones.
In addition to the structure of the stone (open, closed, etc.), the composition of the constituent elements (minerals, etc.) also plays an important role in determining the volume mass.