Carl,
The Hard Pak or Ledge Pak as I know it up around moultonborough is a mixture of blue stone dust and pieces of Blue stone (rocks).
Blue Stone, for those that may not know. Is used alot for outdoor patios, fireplace hearths etc. it can be found in various square sized pieces around 1/2" to 2" thick by upwards of 2 & 3 foot square. I believe that a large portion of the supply comes from PA.
If there are any landscapers out there please feel free to either correct me or supplement my limited knoweledge of Blue Stone.
I usually buy my hard pak / ledge pak mixture from Brox Industries, they have plants scattered about NH. They usually have it mixed seperatly in several sizes of the blue rocks. 3/8's, upto 3/4 depending on what you might want. I was told that they sell alot of the smaller 3/8's mixture for horse riding trails etc.
Some of the local Highway departments use the hard pak / ledge pak on there dirt roads. usually just on the hills to battle erosion problems.
It is extremely popular around here as a finished driveway coating because it not only packs down like concrete, it allows water to quickly drain through and it has a very pretty dark blue color.