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were apparently influenced by the contemporaneous emplacement of the Stony Mountain Stock <br /> as evidenced by their propensity to merge with the radial pattern of faulting surrounding the <br /> Stony Mountain Stock. The dominant rock formation in the Project area is the 35 to 30 Ma <br /> andesitic San Juan Formation. This is a thick package of mostly water-lain volcaniclastic rocks <br /> with minor lava flows. <br /> Water storage and transmission is not driven by lithology but rather fracture flow. There is no <br /> primary water bearing zone, formation, or even intrusion. Historically, when new tunnels and <br /> drifts were driven at lower elevations in the area and dewatered, the upper areas dried out. <br /> Additionally, mine water flows fluctuate seasonally due to infiltration from snowmelt. <br /> The quartz veins that penetrated the San Juan Formation are primarily 1' to 5' wide and are <br /> comprised of up to 20% sulfide minerals with rare free gold and silver. The Virginius vein is a <br /> quartz carbonate structure with acid neutralizing potential. Most of the rock surrounding the <br /> veins is andesite but is lamprophyritic by composition—meaning it contains carbonates in its <br /> matrix. These lamprophyre volcanic deposits are similar in age and composition to deposits in <br /> the Silverton area that are being used to neutralize acid mine drainage. <br /> The quartz veins have four principal metallic minerals: <br /> - galena (PbS) <br /> - sphalerite (ZnS) <br /> - chalcopyrite (CuFeS2) <br /> - Tetrahedrite (CU12Sb4S13)with a variant freibergite which has some silver(Ag) <br /> replacing some of the copper. <br /> 7.4 Groundwater/Mine Water <br /> Groundwater in the Revenue Mine area is almost completely supplied by infiltration of high- <br /> elevation surface water seeping through fracture systems. No sedimentary aquifers are found in <br /> this area. Additionally, the groundwater regime is strongly influenced by historical mining <br /> activity. As such, it is not possible to identify all groundwater sources and flows. From historical <br /> documentation of the Revenue/Virginius mining activity in the area, it is known that only the <br /> original Virginius mining area is located above and connected to the Revenue tunnel. Other <br /> mines are located above the Revenue tunnel, such as the Atlas Mine and historic mines in <br /> Governor Basin, but at this time do not connect to the revenue tunnel. <br /> The primary drivers of the groundwater at the Revenue Mine consist of: <br /> - the old Virginius vein development above the Revenue Tunnel in the Monongahela <br /> workings; <br /> - groundwater intercepts in the historic workings; and <br /> M-2012-032 <br /> Amendment 02 Exhibit U <br /> December 2021 U-18 <br />