On Rob H's blog he posted a pic of "pins and feathers" used to split
rocks.

I did my disertation on granite, so it caught my eye. IDAGS and found
this:

http://www.youtube.com/watch?v=cBMcMGBhUVk

The guy splits a 26,000 lb chunk of granite with a 2 lb sledge in an
hour. Amazing.

See more in ABPW.