This item contains the following correspondence:

1. 28 March 1978. Typewritten letter to Johnson discussing plans to travel to Australia and requesting information about suitable sites to collect minerals and observe flora and fauna in Australia. One page.
   
   
2. 22 June 1978. Typewritten letter to Johnson thanking him for his assistance and discussing planned trip to Australia. One page.
   
   
3. 28 December 1978. Two page typewritten letter to Johnson expressing gratitude for his hospitality and assistance while the Hallahans were travelling in Australia. Included with the letter are three colour photographic prints. One of the prints depicts Johnson standing outside of the South Australian Museum, and a second print depicts Johnson and Marion Hallahan standing outside the South Australian Museum. Both prints carry handwritten annotations on their reverse sides. A third print depicts John and Marion Hallahan near Ayers Rock in Central Australia and also features a Christmas greeting.
   
   
4. 7 May 1981. Typewritten letter to Johnson discussing mineral specimen exchange and lectures about Australia and its natural history given by Hallahan following his return to the USA from Australia, and thanking Johnson for his assistance during their stay in Australia. One page.
   
   

Individuals mentioned in this correspondence include Dr Bill Birch, Chris Johnston, Bill Henderson, and Vince Piesley.