The whole countertop surface is usually sealed for any stone top. Epoxy or something similar. Usually the underside isn’t, that’s where I’d do the test.
And at atmospheric pressure I expect it to decompose well before it melts.
It’s not the best. Same with limestone. Granite is better. Quartzite is even better, if you want to not have to mop up spills immediately. Generally, though, you seal any natural stone countertop at installation and then periodically after that.
The kindling temperature of wood is around 451ºF, so the kitchen would burn down before any stone counter-tops would melt. I think the same test for ivory would work for stone counters: stretch out a paper clip and heat the end to red hot, touch it to the ivory. If it is ivory, nothing happens; if it’s plastic, it will melt.
I have a feeling that the counter top I saw was probably not even a composite. The melt spot looked exactly like melted plastic and was suspiciously shiny. Seems weird, as the place underwent a to-the-studs renovation in 2002. Why they would skimp on counter tops is a mystery.
[QUOTE=Chefguy]
…the place underwent a to-the-studs renovation in 2002. Why they would skimp on counter tops is a mystery.
[/QUOTE]
That part’s easy.
The countertops are near the tail end of a project, well after the demo, structural repairs/restructuring for new floorplan, plumbing, electrical, sheetrock, flooring, cabinets… At some point, someone probably looked at what had been spent so far, realized the mold abatement, replacing rotten joists and subfloor caused by an old plumbing leak put them on the wrong side of the budget and decided to skimp a bit on whatever they could to ease the costs. At that point, about all that’s left is paint, light bulbs and countertops.
Just to drop in. Really, how can anyone mistake fake rock from the real thing? Marble is marble. It’s cold, hard, and just real different than anything made to look just like real marble. Corian doesn’t even come close. Except from 20 feet away, as we used to say in the scene shop.
The best way to gauge whether it’s real or fake, as others have touched on, is the temperature. Marble is the coldest feeling to the touch (even compared to granite or quartz) which is why, even if not used throughout the whole kitchen, you sometimes see it in a small baking area for rolling out dough, because it keeps the dough from sticking. Corian will feel slightly cooler than wood or plastic laminate, but not cold like actual stone.
Hopefully not a full fledged hijack here, but we seem to have corralled a few folks knowledgeable on the different materials used in counter tops
A few years ago, the ex-wife and I redid our kitchen and spent some decent coin on Silestone counter tops. Now, 8 years later, they still look perfect, but I’m planning on selling the house early next year. Will the Silestone be a positive selling point? Neutral?, or will expert shoppers chuckle under their breath?
Depends. Where I live, in NorCal, the “modern look” is very popular, and that often includes “Quartz” countertops. The plus is you don’t have to seal it, and it’s a sleek, clean “not frilly” look. For someone looking for a more traditional look, natural materials will be more of a plus. A good realtor will know how to market it correctly. 
But they should not look dated, if that’s what you’re worried about.
Merely corroborative detail, intended to give artistic verisimilitude to an otherwise bald and unconvincing narrative.
Anything that’s not Formica will be fine. Even then, as long as it’s not all scarred up or badly installed, it will be a plus. We put quartz in our last home and it was a selling plus. This house has poorly installed granite tiles in the kitchen, and it was a negative for me. I’d replace it, but don’t feel like spending the money on something purely cosmetic. I don’t like marble because it’s not only expensive, it’s relatively easily scratched; it would be a negative for me if I was buying.
Granite won’t melt, but it can sustain surface damage from very high heat. It’s a composite stone, and the materials don’t expand and contract at the same rate causing minor surface fracturing. A smoothed piece of granite can be roughened by heating it with a torch. You’d have to take something extremely hot off the stove and put it right down on the granite to make that happen. Marble and soapstone are excellent for heat resistance, if the marble is the right variety.
I’m pretty sure any countertop isn’t full graphite composite, as in aerospace (and other) structures, but…those things melt too, and would look like melted plastic also, no?
“Plastic” is the key word, in that anything that doesn’t sublimate will get liquid-y (plastic) before hardening. But I do understand Chefguy would have said “lava field-y” if he saw it, so melt patterns have different forms.
ETA: Tripolar, granite will melt, if you heat it up enough. I’m more abstract here, not in OP kitchen but Hell’s.
ETA2: I actually live in the East Village, a few miles S of Hell’s Kitchen.
It may disintegrate before it melts. Not that it makes much difference.
Thanks for all the answers. I’m pretty conversant in the construction trades, but no expert with this particular subject. While I was pretty sure this couldn’t be marble, I thought I’d check with all of you.
Graphite melting temperature
Korobenko V.N., Savvatimskiy A.I. (savlab@iht.mpei.ac.ru )
Institute of High Energy Densities (IHED)
Associated Institute for High Temperature
http://www.temperatures.ru/pdf/graphite3.pdf
On liquid carbon: ALS - Advanced Light Source
So now I know.
I’d be extraordinarily wary of marble for kitchen counters; it’s an extremely soft stone (3 on the Mohs scale or so), and just about everything will scratch it, and most acidic things (vinegar, lemon juice, etc…) will etch it as well.
I’d personally rather have laminate, as ugly as it is. (I actually have granite, and it’s excellent.)
“Composite” is not synonymous with “carbon-fiber composite”. Carbon-fiber composite is one kind of composite, but so is concrete, and so is Corian.
So is my identity.