Empire Ridge is a narrow, northeast-trending ridge of silicified rocks extending southwest about 700m from the southwest end of the Apollo open stope. A 175m horizon of lithic tuffs and lacustrine sediments is exposed widening to the southwest for 5km toward the coast at Heather. This unit has been altered to residual vuggy, silicic ribs and lithocaps haloed by patches of advanced argillic alteration identical to hypogene alteration observed at Orange Mountain. The residual silica is cut by quartz-limonite breccias and quartz-adularia ± carbonate breccias that are structurally, texturally and geochemically similar to vein breccias at the Apollo mine.
During the summer of 2016, Redstar spent time generating drill targets on the Empire Ridge/California extension of the Apollo structure, but the area still needs a structural interpretation to confirm those targets. Redstar outcrop samples returned up to 219g/t Au.
In 1979, Resource Associates of Alaska collected six samples, including gossanous float, that returned maximum values of 2.0g/t Au, 1,000g/t As and 49g/t Hg.
In 1983 Apollo Alaska Gold Mines drilled three core holes, one of which intersected 0.6m containing 0.034g/t Au + 20.57g/t Ag, 4% Pb, 3.1% Zn and 0.7% Cu. Copies of assay laboratory certificates show that AAGM excavated and sampled two trenches:
Trench ERT1 was 24m long and contained an interval of 1.5m @ 0.30g/t Au.
Trench ERT2 was 31m long and contained an interval of 3.05m @ 0.18g/t Au.
In 2005, Peter Drobeck reported a sample of gossan that contained 0.573g/t Au along with high mercury and arsenic values (10g/t Hg and 1,632g/t As).