I am also looking at the whit macaubus and don't want it to etch. I am having a sample made to test. Only way to know. I have found some places are happy for you to test on site, one even provided me with ketchup. Other places are frustrating to even get a sample from. Curious to know what you come up with.

It is easy to verify that they aren't marble. Marble is relatively soft and a metal such as steel can scratch it. Quartzite is extremely hard, harder than granite so you wouldn't be able to scratch it with metal. It takes something like diamond to scratch it.

It seems more likely that some Super White (and perhaps some white Macaubus) is a mixture of quartzite and some calcium based mineral.

I feel your pain. Probably spent 4 months agonizing over quartzite. Eventually went with a couple of very nice slabs of Madre Perola quartzite, which have been absolutely bullet proof after 9 months. No stains and no etches. My husband even used Windex on it!!!...no etches. It took me a long time to track down the info I needed to be comfortable with the decision, but the Gardenweb community came through with the info I needed. I've attached a link to one of my threads with some White Princess info. Good luck.

Here is a link that might be useful: Quartzite info

I have white macaubus on my island. No etching or staining. It is holding up great!