Wiktionary
n. stone that is quarry in thin pieces.
Wikipedia
Ragstone (1970–1978) was a British Thoroughbred racehorse and sire. A specialist stayer, he was unplaced in his only run as a two-year-old but won all four of his races in 1973. When moved up in class as a four-year-old he won the Aston Park Stakes and the Henry II Stakes before taking Britain's premier long distance race, the Ascot Gold Cup. After seven successive wins he was beaten in his next race and retired to stud. He showed some promise as a breeding stallion before dying at the age of eight.
Usage examples of "ragstone".
The Romans had built the tower of white ragstone, well-buttressed and founded.
The hill contained a widely disseminated deposit of mineral in apparently evenly consistent presence throughout the rock, which was of igneous type and millions of years older than the sandstone and ragstone of the mountains that surrounded it.
If you were drifting down-river in a boat, so that you could see all nineteen of the squat piers that held the bridge up, and all twenty of the ragstone arches and wooden drawbridges that let the water through, you’d be able to see that this open space—“the square,” it was called—stood directly above an arch that was wider than any of the others—thirty-four feet, at its widest.