It seems to me that Blue John was worked as far back as the Romans.
I recall a picture of a very thin goblet. But the ancients
stabilized it with something, perhaps a tree resin. And I think that
later lapidarists have stabilized with more modern concoctions.
Concerning “Tiffany Stone”, “Fluorspar” would indicate the color,
perhaps, but give no hint of the good workability of the opalite.
The SiO2 gives it a much better hardness,and is the bulk of the
composition of the stone.
Rose Alene McArthur
@O_B_McArthurs