[GURPS Magic] New spell: Refine

[Polkageist]

You can add the proviso that it only works on fresh from the earth, unworked material (Shape earth for ex. costs more for stone, and even more for worked stone). That invalidates any structural stonework that's been shaped by human hands. The spell only works on material that has at most been dug up with a shovel and put in a pile.

[Fred Brackin]

Originally Posted by Polkageist

The spell only works on material that has at most been dug up with a shovel and put in a pile.

That wouldn't work on most ores unless the Mage hung out at a mine a lot.

[Tyneras]

A better balance would be if it extracted the desired material AND replaced it with and equivalent amount of rock/earth identical to what it was extracted from. This removes concerns about demolition and makes it effectively a Create Metal spell with a restriction on where it is cast.

If further limits are desired, then requiring specialization by target metal would be a good option.

[Whitewings]

Originally Posted by Willy

Depending on how hard it is in low TLs to get pure metalls / minerals out of ore, it need to be highly costly or every mining operation or mint would just hire a wizard and a few workers to dig out the stuff.

That might not be a meaningful savings. Even a moderately productive mine produces huge amounts of raw ore; no single wizard is likely to keep up, or be willing to.

[Polkageist]

That wouldn't work on most ores unless the Mage hung out at a mine a lot.

Welp, get used to mines then!

A better balance would be if it extracted the desired material AND replaced it with and equivalent amount of rock/earth identical to what it was extracted from.

That'd put Create Earth in the prereq chain, which feels pretty appropriate. The refined/extracted material is replaced with 'common rock', whatever that might be. Magic can handle the details.

TL gating is good, because as knowledge increases so do the spectrum of known materials. Alchemical base vs. precious metals are also a good structure to base what is and isn't possible.

So X FP per quantity to extract a base metal like iron, lead, or tin. Y FP (Y>X) per quantity to extract a precious metal like gold, silver, or copper.

At higher tech levels, that can expand to include metals like aluminum or lithium for 'common' metals (some rare earths aren't so rare, just annoying to extract), and uranium and other transplutonics for rare, precious (and dangerous!) metals!

[Varyon]

Originally Posted by Polkageist

The refined/extracted material is replaced with 'common rock', whatever that might be. Magic can handle the details.

That probably works better than the initial suggestion of replacing it with whatever it's being extracted from - I don't think you want someone grabbing a chunk of kimberlite, using Refine to extract the igneous rock, and ending up with rock in one hand and a diamond of comparable size in the other.

[Whitewings]

Originally Posted by Varyon

That probably works better than the initial suggestion of replacing it with whatever it's being extracted from - I don't think you want someone grabbing a chunk of kimberlite, using Refine to extract the igneous rock, and ending up with rock in one hand and a diamond of comparable size in the other.

Though that would likely yield a giant industrial diamond, or at most a very low grade gem, barely above dirt grade.

[Polkageist]

Since this is a brand new spell, I'm not sure if it should work on gemstones or not.

On one hand, being able to extract a raw gem from a stone would be an interesting and useful (if expensive) use case. However, other spells in its family don't work on gemstones (ahem, earth to stone) so gems might be that thing that are too special to play with magic that way.

Speaking of limitations, having it only work on extractable, metal-like or 'pure' substances would be appropriate. So you couldn't game subtractive refining like the kimberlite trick by pulling out all the igneous rock, since 'igneous rock' isn't something that you'd normally refine. TL definitely comes into play here, so at today's TL you could do something interesting like 'extract iodine' and you'd get a pool of iodine, but if you did 'extract carbon' the spell would shrug and be like what are you doing you don't refine carbon, that's way too common for my magical powers.

Put another way, the spell has expensive tastes

[RyanW]

Originally Posted by Polkageist

You can add the proviso that it only works on fresh from the earth, unworked material (Shape earth for ex. costs more for stone, and even more for worked stone).

I'd simply say it will auto-fail if cast on stone under structural load. That way you can't use it to collapse a wall or cause a cave-in.

[Tyneras]

If you are worried about getting mega gems via the spell, then having the material come out as sand or dust sized grains could work. With metals no one would care, you just melt it down into a bar afterward. Simple explanation would be that as the unit the spell works in, swapping out one tiny grain of material for an equally tiny grain of common rock at a time.