"The installer also offered to uninstall the slabs we have, dry them out, reseal them, and reinstall them. Is this worth a shot?"

Absolutely not. How are the tops going to dry any faster or better at his shop than in your home? They are not. And what are you going to do for countertops for a month?

Stop fooling yourself and replace the tops.

Thanks @Joseph Corlett, LLC — appreciate your advice.

They acknowledged that they didn't seal the cut surfaces or underside before installation because they didn't think they needed to. So the drying out, yes, no reason it would go faster there, but sealing the cut surfaces and underside is the argument for why it could work if they did this.

They already applied a heat gun to the stone onsite to dry it out before, and that introduced some browning you can see in the left of the photo, which they said couldn't have come from the heat but obviously it did as it wasn't there before.

What I don't know is whether this issue is inherent to this Maldives quartzite (and similar-looking quartzite like Infinity White? anything that's not more "crystalline"?). In other words, did the installer err and there is actually a way to prep and install this and not have a problem? Or would we have a problem with this stone no matter what if it's around a sink?

The safe option from a functional perspective would be to fall back to the manufactured quartz we have elsewhere in the kitchen. We made a lot of design choices around having this stone or similar, though, so it would be a shame to have to do that.

Hahaha... but he's such a looker...

Still, point taken. I am skeptical that they can do anything to make the Maldives quartzite work.

So then the question is — how to identify quartzites that are OK for this application? Soak test with a sample?

" how to identify quartzites that are OK for this application? Soak test with a sample? "

Even "Maldives" from two separate slab yards should be tested, some would argue if using multiple slabs to get a piece of each slab to test. You're dealing with mother nature here and the only rule is there are no rules unfortunately. What makes it difficult is also what makes it beautiful.

This is a guide for quartzite, and you will see a couple ways to test to see whether your stone is quartzite or is actually marble or will behave like marble.

http://usenaturalstone.org/definitive-guide-quartzite/

This article is a bit more relevant.

> You're dealing with mother nature here and the only rule is there are no rules unfortunately. What makes it difficult is also what makes it beautiful.

Helpful perspective @millworkman — thanks!

And thanks @M Miller and @Joseph Corlett, LLC for the articles. I'll try these tests and look at (guess at) the classification in making another selection.