As part of his work on terraces....Spiral has developed a unhealthy interest in stones and quarries...It's a bugger knowing where to start as orthodoxy appears equally baffled....
Basically everyone accepts that the Ancients were using a lot of wood...Then along potter the Romans who would have (by common consent) needed a lot of stone, gravel etc...not least for their roads and some urban building, along with the odd villa...but nobody really knows where it came from (unless it's Purbeck marble).
The archaeologists haven't helped, until recently by showing little interest in "low status" stonework and guessing where the high status stuff has appeared from.
Your canny ancients were probably adept at passing off the bad for the good....a practice that appears to have carried on till the formation of THE... British Stone Classification (Stone Federation GB)
"There are many different classification schemes for stone, which have prompted the industry to simplify descriptions. This has led to many problems when, for instance, a stone laid as a granite is actually found to be a different stone type altogether and does not perform as expected. The British Standard BSEN12440 (Denomination of natural stone) addresses the classification problem and insists upon the correct identification of stone type and origin."