Ask for the remnant and repeat. And get all the sealant info.

What quartzite?

I have Taj Mahal and it doesn't really need to be sealed.

My designer didn’t want to take chances and wanted it sealed, but I will ask for an unsealed remnant and try.

It was sold to me as “Copacabana Quartzite,” but my research indicates that a lot of quartzite names are made up. Googling copacabana quartzite gives a lot of jet black natural stone with dramatic white veining, while my slab is clearly grey/white with white, black, and even some olive and rust veining.

This is one of the slabs and the kitchen so far.

Here’s the etch test before/during/after

Very nice. I have seen similar with different names.

The name Copacabana makes a lot more sense with a black and white quartzite ... named after the black and white sidewalks of Copacabana Beach in Rio, Brazil.

The color you have, would be called a "white" quartzite and those should definitely be sealed, just in case.

Theres a few things going on here. Etch test is testing the chemical composition of your slab, basically asking: is it actually marble? if it etches, its marble - doesnt matter if its sealed or not. it didnt etch so you are in the clear on that. second question, is it porous, meaning does it absorb water? that is what can lead it to stain, and what the sealer helps prevent. when you get an unsealed fragment you can test the porosity, or just err on the safe side and seal whenever it stops repelling water