What do I need to cut the rocks to get level surface for laying on top of each other? I don't know what they are exactly but I live atop of limestone bedrock but these rocks are grayish with what appears to be tiny quartz on the surface. Very dense or extremely hard to break with my heavy hammer and chisel unlike those chalky types. Is there such thing as gray limestone? I get all free rocks from undeveloped land behind my backyard where the builder apparently dumped rocks when they built this subdivision. The problem is that the rocks come in all shapes and sizes!

Can "semi-mortared" be used mainly to keep them together while draining away the water? Mainly I just want flat surface to lay on the base. Thanks!