This was usually granite or limestone. The most common igneous rock is granite. Marble, quartzite, and slate are the metamorphic rocks most frequently quarried. Sedimentary rocks include sandstone and shale. Limestone, marble, and granite are still much used for buildings and monuments.
Slate is used for roofing and quartzite for flagging.
Crushed stone is used for concrete and road building. The quarrying technique involves deep drilling and blasting to break the rock. When usable rock is found, the surface is cleared. A cut, or channel, is made to separate the rock from the solid bed, or mass. Large blocks are separated from the parent mass, sometimes with the use of low-powered explosives.