GEOMETRY files, usually in the form NAME.GEOMETRY.MBIN.PC are MBIN files contaning 3D model data. The Blender Import Plugin is responsible for writing all data here, rather than doing so manually and as such, the GEOMETRY file is usually left untouched. An empty SCENE will work but still require an empty GEOMETRY file. On the other hand, No Man's Model Viewer is also capable of reading these files as well as exporting to a more usable *.obj file.