Fonds consists of mostly glass plate negatives and some glass plate transparencies. The images are from locations where John A. Johnston resided and worked. The majority of the images are of mine pit locations and wilderness scenes. There are also some images of unidentified people and buildings in Toronto.

For a more detailed description, use this link to the Archives of Ontario's descriptive database: http://ao.minisisinc.com/scripts/mwimain.dll/144/PROV/PROV/REFD+C+155?SESSIONSEARCH