Fossilised shell and coral in a pale cream field — coastal by literal composition.
Shellstone — also sold as coral stone or Yucatán limestone — is a young sedimentary stone full of visible fossil shell fragments. Look closely at any piece and you will find whole small shells in cross-section. It is the most literally coastal material in this library.
It is exceptionally cool underfoot and it grips well wet, which is why it has become a signature pool deck material through the Keys and the Gulf coast. The pale cream field reads bright without the glare of a true white.
It is also the softest and most absorbent stone here. It scratches, it takes stains readily, and it needs real sealing discipline. That fragility is inseparable from the fossil texture people buy it for.
Post the project and contractors working in your county bid on it — with this stone already specified.