Basically it's like this. For example, CuSO4·5H2O is called bile vitriol or blue vitriol, FeSO4·7H2O is called green vitriol, KAl(SO4)2·12H2O is called white vitriol, etc. And Na2SO4·10H2O is called Glauber's salt.
Does it mean that so-and-so has to be two words and cannot be so-and-so? "Na2SO4·10H2O should be called sodium vitriol sulfate." You really know how to name this. According to your logic, shouldn't Na2SO4·10H2O be called so-and-so alum? !
Sodium carbonate crystals do not contain crystal water, so there is no such substance as sodium carbonate decahydrate.
This is the first time I have heard of Gong Alum. I searched online and some people said that Gong Alum is sodium carbonate rather than sodium carbonate decahydrate.