[RPG] Functions of special materials

Unfortunately, there doesn't seem to be a hard RAW answer to this so it is left to the DM's discretion to extrapolate from similar abilities.

Obvious answer to me is "No" although this is a transmutation and therefore actually does constitute the material actually being silver for the duration it indicates in the creation of Holy Water that it requires Silver Dust. A DM can therefore rule that each speck of dust is an individual object (which they technically are) and thus only one speck can be transmuted.

A DM is free to rule that scraping flecks off a transmuted object also revert to their previous makeup as those pieces are no longer subject to the power being a separate object.

Your DM's mileage may vary but this is tricky and can be a source of abuse albeit this assumes being able to find a buyer for the Holy Water at face value and procuring materials that would provide enough dust to create it. And of course time away from adventuring.

It would obviously be more abusive to be duping a merchant or money changer into purchasing the silver outright. Since one cubic foot of silver is 654.91 pounds which at 5gp per pound is 3274.55 gold piece in trade. It would be likely be widely known about magic and there would be tests or holding periods before payment would be rendered to the wizard as well. This of course is a bit outside the scope of the question but was worth mentioning as an argument on ways to abuse the ability.

The answer is going to depend on whether the spell is still in effect when the reversion happens.

Fabricate

Fabricate is instantaneous. You cast the spell, the magic shapes the material, and then it holds that shape forever just as if you'd cast it or carved it.

The result of transmuting some cheap wood to fine silver, then Fabricating it into high-quality jewelry, then having it revert back, is that you now have fine jewelry made out of cheap wood. The delicate shapes are not going to hold up to wear. It's going to have the grain structure of the wood, which may be too coarse to show the details you want. It may have material flaws like knots and pockets of sap.

Fabricate has the limitation that making high-quality goods requires crafting proficiency appropriate to the thing you're making. I'd say that in this case, if you're proficient with both jeweler's and woodworker's tools, and knew that the silver was going to revert to wood, you could end up with high-quality woodcrafts. Otherwise you're going to get junk.

Meld Into Stone

This has a duration of 8 hours. It also addresses this issue:

Minor physical damage to the stone doesn't harm you, but its partial destruction or a change in its shape (to the extent that you no longer fit within it) expels you and deals 6d6 bludgeoning damage to you. The stone's complete destruction (or transmutation into a different substance) expels you and deals 50 bludgeoning damage to you.

So, good luck with that.

Mold Earth is instantaneous--kind of, sometimes.

The basic use of Mold Earth is like a magical shovel: it takes a chunk of dirt or stone and moves it.

But it also has those persistent effects that last 1 hour. My initial reading was that the spell reshapes the soil to achieve those effects, instantaneously, and then they disintegrate after an hour as the soil returns to its natural state, like a sandcastle. But you can dismiss the effect, which implies that the magic is still doing something. I could see a DM ruling either way on this.