Near-black with hard white veining. Pure drama, used in small doses.
Nero Marquina is a deep black Spanish marble crossed by sharp, high-contrast white veins. There is nothing subtle about it, and that is the point — it is an accent stone, used where a room needs a single decisive gesture.
It is at its best vertically and in small fields: a fireplace surround, a powder room floor, a bar face, a stair riser. Run across a large open floor it overwhelms almost any furniture placed on it.
Black marble is unforgiving of dust and of water spotting, and every etch mark shows as a pale scar. Specify it where it will be seen and admired, not where it will be scrubbed.
Each of these opens the library filtered to everything suitable for that use, so you can see what Nero Marquina is competing against.
Post the project and contractors working in your county bid on it — with this stone already specified.