First let me clearly state this is not a proposal to change the rarity/value/difficulty of finding or obtaining metals, that falls under balance discussions and not what I'm trying to address in this thread. I'm just proposing what I believe to be a simpler and more intuitive way to prospect, any desired rarity of metal can be achieved under this proposed system by tweaking some simple values so please do not derail discussions with complaints that this proposal makes prospecting too hard or too easy.
Main Points
* Rust Root and its extract are eliminated
* A Character with prospecting revives a new "Prospect" option in addition to chip stone when selecting a bedrock slab, Prospecting can't be done on Boulders removed from cellars though.
* The Prospecting action results in the 'Radar Scan' effect previously created with Rust Root Extract
* The Radar effect is greatly reduced in radius, the area scanned would probably be less then the screen area at low level
* Perception and Exploration act to expand the radius of the scan but the effect is none linear and would have diminishing returns so the radius remains smaller then the mini-map even at highest level,
* The player would be shown a circle on the mini-map showing the radius of the scan while the Prospect labor is being performed
* A new Terraform option "Expose Bedrock" is available to anyone with Mining, it can create a Bedrock slab on any ground and is a long and exhausting task
* A Bedrock slabs that have been prospected and come back at 100% will have a "Build Mine" option replace the Prospect option, anyone may build the mine with this option but it will revert after a few minutes if not used
Prospecting would be much more intuitive for a new player, they would see the Prospect option while playing and have a better understanding of how it works. The prospecting process would still be one of searching but rather then searching for a rare plant the prospector would be wandering around and examining rocks. Finally the ability to create new Bedrock slabs both allows the triangulation of the ore body by creating additional prospect-able locations it also eliminates the irreversible loss of slabs when a rune-stone is created. Balancing rarity would be done by adjusting the radius of scan, particularly with regard to the effect of Perception & Exploration on the radius and of course the actual number of metal ore occurrences in the world.