Sandstone from White House
Potomac Formation. A microscope photo of the sandstone reveals that it contains too much clay to be very durable. It also has other flaws (not visible here) that can cause big problems for a building stone: isolated large pebbles and clay lumps, and uncemented areas.
Image Number: 2002-21820
Catalog Number: 113606
Gift of Architect of the Capitol
Locality: Aquia Creek