The Prospecting Pick Command is:
/worldConfig propickNodeSearchRadius 8
You can replace 8 with any number up to 12 to increase or decrease the range.

Prospecting is a huge part of Vintage Story, and I hope this video helps make it clear how it works and what you need to succeed in it. The actual act of prospecting is lengthy and so I had to use a lot of editing to fit the process into 10 mins.

While I was searching for Copper here, this works on all Ores except Halite which spawns in giant vertical pillars and is immune to Node Search (Because its just rock not ore) and Alum which only spawns extremely rarely in the desert (Seriously I have straight up cheated 1000's of times to just delete all the stone and fly around with the propick and never found Alum lol)

Some advice: While I got sloppy here due to terrain, try to stay locked down to the same X Coordinate while moving in a direction, to remain consistent.
Moving 80 blocks at a time is a good distance to check.

FAQ:

Q: Does this work on Tin?
A: Yes! Tin is Cassiterite. I plan to do a video on finding it on it's own but this method is 100% the same you would us on Tin. Keep in mind tin rarely goes any higher than 0.2‰ so focus on the Adjective!

Q: I searched Everywhere but there is NO Copper
A: It's a matter of bad luck entirely. You have no choice but to gear up and head even deeper out to try and find a reading. Keep in mind, even a reading of Very Poor 0‰ is enough to begin chasing

Q: Why do some of these Ores have weird names?
A: Vintage tries to be accurate and educational. If you're ever confused what the heck "Pentlandite" is open the info log and actually click on the name, it will show you in the Handbook what it produces

Q: I still don't understand. It went by too fast in the video
A: Check out this long form older video where I do it in real time with no edits:    • How To Find Ore in Vintage Story: Rea...