Marble names that are not what they say: limestone, dolomite and serpentine
Nero Marquina is a limestone, Verde Alpi is a serpentinite and Super White is often a dolomite. Why stone names mislead, and why it matters for your worktop.
By the Ajusteur teamUpdated 4 minute read
Why are stone names so loose?
A geologist and a stone yard mean different things by marble. To the trade, a stone that can be polished and has a marble look is a marble. Names are trade names too, and the same stone can be sold under several. So treat the name as a starting point and the record as the truth.
Black and beige marbles that are limestone
Nero Marquina, from the Basque Country in Spain, is a fine grained compact black limestone with white veins and fossils. Sahara Noir from Tunisia and Crema Marfil from Alicante are compact limestones sold as marble as well. Limestone is calcite, like marble, so acids etch it. On a black polish the marks show grey.
Sahara Noir has one more quirk: one processor notes it is not very compact, so slabs are coated with resin to hold them together. Keep hot pans off the resin.
Source: Brachot: Sahara Noir
Green marbles that are serpentine
Verde Alpi from the Aosta valley is a serpentinite breccia. Verde Guatemala, despite its name, comes mostly from Rajasthan in India. Green Prada is a trade name rather than a quarry: suppliers variously give Italy, Taiwan, Greece or Brazil as its origin.
Serpentine changes how the stone is fixed. Green serpentine stones can warp or stain with water based tile adhesive, so they are fixed with epoxy or a rapid set adhesive. Tell your fitter before the bag of thinset comes out.
Source: Brachot: Verde Alpi
What a geological survey says about green marble
Vermont has quarried a green stone sold as Verde Antique marble since the nineteenth century, and the state's geological survey is blunt about the name. It calls Verde Antique the commercial name for a dark green serpentine crossed by shear fractures filled with white calcite, and says that though the common name is marble, the rock is a metamorphosed magnesium silicate related to talc and chlorite. The survey also notes its hardness and beauty suit it to tiles, countertops, sinks and facades.
Two lessons travel from Vermont to Dubai. First, the green body of these stones is not calcite, so it is harder than marble and does not etch the way marble does. Second, the white veins that make the pattern are calcite, so lemon juice still dulls them. A green serpentine worktop keeps its colour and loses the shine of its veins. The same is true of Verde Alpi and the other green marbles in our records.
Quartzites that are dolomite
Super White is widely sold as a quartzite. One stone processor classifies it as a dolomite marble. Dolomite etches more slowly than calcite but it does etch, so it is not the acid proof worktop a true quartzite is. The same processor warns that not every stone sold as Taj Mahal is real quartzite.
The kitchen test settles it. Leave lemon juice on a sample for a few minutes, wipe it off, and try a knife on the surface. Quartzite stays shiny and unscratched. Dolomite and marble will show a dull patch.
Source: Brachot: Super White
What to ask before you choose a slab
Four questions get you past the name.
Where to look them up
Each stone in our marble and natural stone library says what it really is, where it is quarried and where it works in a home. For the worktop question in full, read is marble a good kitchen worktop.
Quick questions
Is Nero Marquina real marble?
Geologically it is a compact black limestone. The trade sells it as marble because it takes a polish. Acids etch it like marble.
Is Super White quartzite or marble?
It is often sold as quartzite, but at least one stone processor classifies it as a dolomite marble, which can etch. Test a sample with lemon juice and a knife.
Why does green marble need epoxy adhesive?
Green serpentine stones can warp or stain with water based adhesives, so fitters use epoxy or a rapid set adhesive.
Does green marble etch?
The green body is serpentine, a silicate that acids do not etch. The white veins are calcite and do dull with lemon or vinegar, so the pattern loses its shine before the colour does.