Looks like marble to me.

They can call it anything they want. Only way to be sure what it is is to get a sample piece and run your own tests on it.

What @millworkman said. Here’s an article that explains how to test a slab.

https://usenaturalstone.org/how-to-be-your-own-stone-sleuth/

They get to charge more by calling it quartzite!

Calling it granite = outdated look , but quartzite = updated look!

Scratch the surface near an edge with a glass tile. Quartzite won't show a scratch.

Looks similar to Fantasy Lux quartzite:

Let us know what you find out - it is really a striking piece of stone!