Also consider visiting:
Your local monumental mason for offcuts of
rocks used for gravestones.
Your local builder's merchant for sand, gravel, guttering etc.
Builder's sand is mostly medium to coarse-grained while sharp sand
contains a wider range of grain sizes. Both need washing to remove
mud before use in investigations; this is done by running a hose
through a bucket of sand until the water which overflows is reasonably
clear. |