hmm.. not sure I follow this, gutta starts out as a latex, but it is changed and used as several different forms. You say rosin. rosin, if I am correct with the term, is also something made from trees and pitch etc. The old mantel clock casements made from Gutta are considered a type of resin, pre bakelite. Yet they are still gutta. Heating anything gutta will change the structure dramtically, making it soft. I think the marble is Gutta. We (the IAMC) sawed one in half. It gave off sparks! I think the basic confusion is trying to figure out what else it was mixed with!Pure gutta? probably not, composite with gutta? I believe that gutta is pre-elastolin. gutta was being used as early as the middle 1800's, where as elastolin wasn't being used until the 1920's or so.(without looking it up.lol)
just a thought anyway.........