Hello all.  A friend of a colleague of mine is looking for information
regarding what might be early photographic materials.  She wrote:

"A friend has some old glass
plates with a black powdery material on the back,
with sketches of some of the old Ishpeming
mines. I assume they were for making photographs,
but am not sure. He'd like to get a little
history on them."

Any thoughts?  Many thanks for your input.

-T. Arron Kotlensky