The .7z.003 extension indicates it is the third part of a split 7-Zip archive. You need all parts (001, 002, etc.) in the same folder to extract the contents using 7-Zip .
The file is a specific multi-part compressed archive segment, typically associated with large-scale geological or seismic data released by Mineral Resources Tasmania (MRT) . File Context and Content SS-Tas-017_s.7z.003
Ensure you have parts .001 and .002 . The first part usually contains the central PDF or text report explaining the survey's findings. SS-Tas-017_s.7z.003