Picture this: you are mining ores, and on the radar you see one. But, when you get to it, you see it is hidden in a large tree, or rock.. or just deep in the ground. There is no way to select it with your cursor.
What you can do is just walk on to the next one… but, you might miss out on a rare shard.
This is the way to get the contents of the deposit.
Rightclick Open, and you can mine the deposit.
You can also use this method for talking to NPC’s.