Old photographic historical processes exists in many forms, not limited to the major movements that arrived only from daguerreotypes, calotypes and the offspring from the wet plate collodion.
One of my recent pieces which I had picked up was an interesting bit. It is a small white slate, which could be a small piece of white marble slate. On one side, there’s a portrait image of a woman, with hair do which suggests late 19th Century or early 20th century. Though no more details could be made other than what was seen. It is sepia in tone, with hints of scribble below her neck which suggest some sort of attempt to “decorate” to be a part of her dress.
It could be a form of opalotype, a white positive, shot from a glass negative, made on milk white plate. Though I am having doubt as it has a silky luster surface, unlike commonly used varnish. For all I know it could have been a part of photographic image that could have been taken off from a head of a gravestone, as the sides were haphazardly chiseled.
An interesting bit of collection…