Sure. And if there are any kinds of rocks that are especially similar but not what you want, those too, so I make sure to get the right thing.

All right. That'll be a tremendous help to them all by itself.

Good.

He starts fixing the rest of his hands.

She putters around taking care of chores for a while and then goes to the jungle to look for a suitable place to put the Eldar's portal; it takes a couple hours for her to settle on a nice cliff face.

He falls asleep again.

She jerky-ifies some more meat and goes for a walk around the lake and realizes that she could be spending this time getting closer to the elves' village so they can teleport to or past it and gets a few hours' progress made on that. It's nearly sunset when she returns.

He's awake and singing to himself again. All well?

Yup. Any news?

They can get you iron ore, and also stone of the kind they'd like to find quarries for. 

Sounds good. It's not 'they trust her' and she's not taking it as that, but it seems like a step in that direction and that's definitely nice.

They will go through portals to good sites for mining, if the Mithrim side of the portals is small enough that people can only squeeze through. 

Portals can be pretty much whatever size - she has an upper limit but 'big enough for two carts side by side with comfortable clearance between them' isn't close to it - and making the portal small isn't a very good security measure. Passwords are a better one, if they'd like.

Still requires trusting her.

She's not going to insist unless they want portals offworld, even if password-protected seems strictly better than not; whatever they want to do is fine by her.

They definitely want password-protected, with "I swear I have never served the Enemy" as the password. Can she alter the password? Alter size?

She can set a spell up so it can be deactivated and then cast a new one that's different later, or she can cast two spells in the same spot that take different passwords and act differently. She can't alter a spell once it's been cast, but the first option does basically the same thing anyway.

They would prefer it unalterable anyway.

Sure.

Breaking spells is a thing, they probably want to know about that. There's only a limited amount she can do about it, but it's unlikely to come up for a spell on stone anyway, and she's doing what she can to make the spells as permanent as possible.

They will happily ask her hours and hours about her magic system and whether such-and-such experiment has been tried.

It was approaching bedtime when she came. She can come back the next day, though.

They have some really good ideas for experiments, and also she eventually gets around to actually casting the portal spells they want. When she's done with that, she stands back, considers for a few moments, and...

It seems to me that that's proof enough that that sentence is pretty safe. I still don't think my species can swear, but: "I swear I have never served the Enemy." For whatever that's worth.

It does relax them visibly. Thank you.

You're welcome.

Any more spells you'd like me to cast today?

Portal to an uninhabited habitable world? Or is that too challenging?

'Too challenging' isn't the problem there; the fact that she can't even slightly guarantee that an unknown world is safe is the problem. Also checking that a world is uninhabited is a two-step process so even if they come up with a way to check safety it's going to take a while to find one.