Gridded Data Transfer:

The grid is presented in Geosoft Oasis montaj (proprietary software) binary format, 
with two files describing each of the grids (suffixes .grd and .grd.gi). The .gi file 
contains information about the projection used by the software. This grid format can 
be converted to numerous other formats using the downloadable free software offered by 
Geosoft at <http://www.geosoft.com>. Below is the projection information for the grid 
as defined in the Geosoft format.

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Projection              Transverse Mercator (Spherical)/DNAG 
Parameters:

Length units                        meters
Longitude of natural origin        -100  0 0.00
Latitude of natural origin            0  0 0.000
Scale Factor at natural origin      0.926
Major Axis, Eccen, Prime Mer        6371204.0, 0, 0
False easting                       0.00000
False northing                      0.00000
--------------------------------------------------