Updated Mineral Resource Estimate At Gunnison Copper Project

VANCOUVER, BC - Excelsior Mining Corp. reported updated mineral resource estimate at the Gunnison Copper Project in Arizona. The prior North Star mineral resource has now been updated to include the results of 13 additional diamond drill holes, totaling 17,110 feet that were completed in December, 2014. The drill program was designed to convert a large part of the inferred mineral resource into the measured & indicated mineral resource categories.

The combined measured & indicated mineral resources estimate has increased by 26.6% as a result of the conversion of some of the 1.39 billion pounds of Cu (388 million short tons at 0.21% Cu) in the inferred mineral resource category into the measured & indicated categories.

The total mineral resource estimate for the North Star Deposit is based on results from 122 drill holes totaling 158,785 feet and is effective as of June 1, 2015. Mr. Michael M. Gustin, with the independent firm Mine Development Associates of Reno, Nevada, is a Qualified Person as defined by NI 43-101 and is responsible for this mineral resource estimate.

The North Star mineral resources were modeled to respect the detailed lithologic, structural, and oxidation modeling completed by Excelsior. Copper mineral domains were interpreted on 100-foot spaced, east-west vertical cross sections that span the 2.3-mile north-south and 1.3-mile east-west extents of the deposit. These domains were then used to explicitly constrain the estimation of copper grades into 50 x 100 x 25 foot (x, y, z) model blocks using 20-foot composites and inverse-distance interpolation. The grade estimation is further controlled by the incorporation of a number of unique search ellipses that reflect the various orientations of the modeled structural zones, as well as the strike and dip of the favorable stratigraphic units in areas unaffected by the structures.