As a professor of graphic arts, my father was an inveterate collector of all things related to printing, an enthusiasm that washed down to my own generation. Our favorite method was letterpress -- where the letters or images are raised above the surface of the printing plate to accept ink rolled or pounced over the top, like a rubber stamp. But just to make the collection comprehensive, Dad acquired some lithographic stones.
The printer must have had to do a lot of tricky masking to make sure just the right one got printed! In those days, financial papers typically included a blank space for the date, printed like this: _______________ 190__. Maybe a clever way for the printer to insure that people came back and had new letterheads printed at least once per decade.
I was reminded when I pulled the stones out for photography just how heavy they are!! My brother, who lives in Australia, reminded me the last time he visited that one of the stones actually belongs to him. I told him he was welcome to take it home with him, but since he's always just a nanogram this side of the weight limit, he declined. So I think both stones are going to stay with me forever.