The lowdown on Super White
I am mostly a lurker here so far, and as our kitchen remodel plans take shape I have been enjoying seeing other people's progress and taking comfort that there is a strong community of kindred spirits who like to sweat all the glorious details of a kitchen!
I'm a geologist so perusing the slab yard is always fun. Rarely do you get to see so many fascinating rocks all in one place.
So today when I picked up my backsplash tile and put down a deposit for some small slabs (a separate story), I had a great time visiting various slabs with one of the fabricators. We talked about the minerals and textures that make some rocks winners in the kitchen, and others not so good.
I asked to see some Super White, knowing there is a lack of clarity about what this rock really is. He gave me a piece to bring home and I did some diagnostics. Maybe this is common knowledge to you all, but here's the lowdown.
The rock is dolomitic marble. It's not quartzite - it's not even close to quartzite in terms or hardness or resistance to acid.
Dolomitic marble is a sibling to regular marble. Regular marble is made of calcite. Dolomite is made of calcite plus magnesium. Calcite is CaCO3 and dolomite is CaMgCO3. So this rock started out as the sedimentary rock called dolomite then was metamorphosed (heat + pressure) to cause the grains to recrystallize into dolomitic marble.
My hunch is that this marble would be slightly more resistant to etching than regular calcite marble. But it is still just as soft as marble and has all the other requirements of caring for marble. It sure is a beautiful rock. But no way will it wear like granite or quartzite.
The decorative stone industry has a whole different way of naming and classifying rocks than geologists do. (The first time someone showed me a back granite I protested loudly. There is no such thing as black granite!) But I am coming around to understand how the rocks are classified from the countertop point of view. So yes, the terms are contradictory and confusing, perhaps even deliberately so in some cases. But at least in this case I am certain of what the actual rock type is.
I hope that's helpful or illuminating. And if you have questions about the real identity or geologic history of your countertop, I may be able to shed some light!