Indentifying White Plate Glass Photo

[waypoint11]

I have a older peice that is on a white glass plate. The glass seems brittle and almost like a coated piece of paper. The front side of the glass has an eggshell like finish while the back side is glossy. Im at a loss at identifying this and you guys seem very knowledgeable. Any help is appreciated!

 

[MDR]

Your photo might be an toovytype also known as Ivorytype
Follow the link below for more informations
http://albumen.conservation-us.org/library/c19/toovytype.html

Dominik