Article on Joel Poinsett trying to push out Spanish from Mexico for access to Mines

I ran across this article on how some person name Joel Poinsett, French or English trying to push out Spanish from Mexico for access to the mines.

http://mexfiles.net/2007/03/29/buried-treasure/

De Ysalba

Does anyone know if the surname de Ysalba or de Esalba is a variation of de Alba?
I've got marriage entries for Maria de Ysalba with Joseph Feliz de Arrambide 02/20/1724 and 03/19/1720 in Mexico, D