For me it feels tedious to dig a huge hole in the soil or gravel to get to the single stone block to propick it. As i know in real life geologists examine and break loose stones found on the ground to get the general impression of what they can find under the ground without actually digging.
I think it would be nice to get that ability in the game. Like you use propick on a loose stone(or three) and it gives you some less precise info about possible ores in the chunk.
Or even better loose stones can be just included in the list of blocks that can be propicked with the first mode.