This is a wonderful picture of Felyn-y-Groes Water Wheel Mill, which is what it states on the reverse of the picture, but I can find little on the web about it, does anyone know?
The picture is over 112 years old,
The crystoleum, from "crystal" + "oleum" (oil), the process was a method of applying colour to an albumen print, popular from c. 1880 – c. 1910
An albumen print was pasted face down to the inside of a concave piece of glass.
The image was then coloured by hand, using oil paints. Another piece of glass was added to the back and this could also be coloured by hand. Both pieces of glass were bound together creating a detailed, albeit fragile, image.