2017 EDIT -- I don't know if this has anything that's not mentioned above. This was a couple months after what I wrote above, so maybe I was trying to write a clean draft and didn't get far, or maybe it was new stuff. Well, it's another link to play with.
About sulphides
Specifically about the name "Sulphide". I wondered how and when figure marbles came to be known as sulphides. Couldn't find much in my normal online search areas. I found just enough to make me suspect that the name came through the French.
1928
L'art et le goût sous la restauration, 1814 à 1830
Jacques Robiquet
Payot, 1928
"«Camées Incrustés », des soi-disant « Sulfures»" ===> "'Cameos Encrusted', with so-called 'Sulphides'"
(Translation by Babel Fish)
http://www.glassmessages.com/index.php?action=printpage;topic=34850.0