}
JHN can you elaborate on the class/ grading of rock R8? and or others . I may have got a few deals but I know little on sale of rock and classifications.
I mostly work with granite, so I don't think they really classify river cobble this way. The smallest I use is R3 (6" and under rock called Gabion), R4 (6"-12"), then it starts going by weight, R5 (50-300lb), R6 ( 300-800lb), R7(800-1600lb.), R8 (1600-3000lb.)
The classification means roughly 90% of the rock is this size, with a few smaller and some larger. This applies mostly with the smaller rock that is loaded with a loader.
Once you start getting the larger sizes like the r7 and above it is loaded by excavator one or two at a time, which of course drives the cost up around $8-10 a ton. However, just about all the rock is in the appropriate size range, except for a rock or two put on to get the load up near the appropriate weight limit.