GR translation: slime stone

[Mike Jing]

P171.35-41   . . . and Maud, dear Maudie, swallowing, wastes not a
drop . . . smiling quietly, unplugged at last, she returns the
unstiffening hawk to its cold bachelor nest but kneels still a bit
longer in the closet of this moment, the drafty, whitelit moment, some
piece by Ernesto Lecuona, “Siboney” perhaps, now reaching them down
corridors long as the sea-lanes back to the green shoals, slime stone
battlements, and palm evenings of Cuba . . .

Is "slime stone" stone covered in slime, or something else entirely?