What counts as "loose earth" for the Mold Earth spell?

Question

The Mold Earth cantrip offers the following option:

You choose a portion of dirt or stone that you can see within range and that fits within a 5-foot cube. You manipulate it in one of the following ways:

• If you target an area of loose earth, you can instantaneously excavate it, move it along the ground, and deposit it up to 5 feet away. This movement doesn’t have enough force to cause damage.

(plus some other options)

What is loose earth?

For example, which of the following would meet this criteria:

• Top soil of a recently plowed field
• Digging a 10 ft hole in the middle of said same field
• Digging a 10 ft hole with a mixture of dirt, gravel, clay
• Digging a 10 ft hole in a cobblestone road
• Digging a 10 ft hole in solid stone
• Digging a 10 ft hole under the foundation of a building

As an analogy, would it be accurate to say that this spell would work on anything in minecraft that I can use a wooden shovel on (with the exception of snow)?

See also: Is it possible to create a sink hole with mold earth and a portable hole?

Answer 1

Jeremy Crawford has already provided some insight to this:

Think dirt, not stone.

Basically, if you can use a shovel on it, you can use the cantrip.

Answer 2

Ask your DM

You have cited the only rules related to "loose earth" in your question. No further details are given in the spell or in any other rules. When a term is not defined in the rules, it defaults to its idiomatic meaning, which does give us something to go on.

Specifically the word "loose" here implies that this is not solid, restrained, or compacted "earth".

So the answer to

Digging a 10 ft hole in solid stone

Is clearly "no". Stone is not at all loose and would thus not fit the definition.

Jeremy Crawford has also agreed with this assessment with this clarification:

Think dirt, not stone.

On the flip side the answer to

Top soil of a recently plowed field

is clearly "yes". I can't imagine a better example of the idea of "loose earth" than recently tilled soil.

But there is where the clear answers end. All your other examples are going to vary based on how your DM interprets the phrase. How loose does earth need to be to be loose? Can it contain soil and small rocks? Clay?

Only your DM can answer these; the rules give no further guidance.

Example: Foundation of a building

Since you are specifically interested in this use case I will address this directly (even though the answer is the same as the above).

Digging a 10 ft hole under the foundation of a building

There are questions here that are dependent not only on DM interpretation, but the precise situation as well. What material is the building built on? Is it built on solid rock? Loam? Swamp? Is this a massive stone castle or a small wooden shed (which changes how "loose" the stuff under the building is)?

None of these questions are answered by the rules. They are thus left up to the DM.

This is one of the ways 5e is specifically designed. Instead of writing precise definitions to have to account for all the possibilities of using the spell they left it vague so the DM could decide on the most fun interpretation for their group.

Answer 3

I'd say a good rule of thumb is that anything that could be dug and moved with a shovel could be dug with Mold Earth. Sand, soil, gravel, etc. Useful cantrips tend to magically replicate mundane activities.

Answer 4

I would allow some flexiblty with the spell to retain its gameplay usefullness. It is Dungeon and Dragons not Farming and Cattle. I would allow the player to attempt to focus that same spell energy on to a smaller mass. The player would make a concentration check and the area would be much smaller. Think about how much soil you moving easily with your mind, a 5ft cube of dirt, that's a large excavator's bucket worth. And you could do than at will all day long. So with that kind of energy and with a concentration check(which becomes an effort action subjected to exhaustion rules) I would allow a player to move a small area of stone, say a 5 inch cube. Magic is much closer to physics than grammar class.