This series contains Johnson’s mineralogical correspondence. It includes a wide variety of material, including correspondence with other mineralogists in Australia and overseas (both amateur and professional) as well as photographs, postcards, draft papers and other material.

Most of the correspondence in this series was sent to Johnson by other mineral specimen collectors in relation to the collection and exchange of mineral samples, particularly micromounted specimens. Some correspondence also relates to general mineralogical and geological subjects, and some relates to the age and distribution of australites. It appears that many people initiated contact with Johnson from around the world, following publication of articles in various journals, and expressed interest in exchanging samples with him. In some cases, the correspondence continued for many years after this initial contact.

Johnson was a prolific correspondent, usually making a careful note of the date of his reply on each letter.

The correspondence in this series has been collated into groups for each individual correspondent, organised alphabetically by surname, then listed and described in chronological order.