2022-02-09_PERMIT FILE - M2021046 (5)

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AMM qW GEM SERVICES Dawson Project—Tailings Characterization Page 3 All material types were subjected to static tests. Acid generation potential was assessed using the modified Sobek method of acid base accounting(MEND, 2009). Short term metal release was assessed using the shake flask extraction procedure (MEND, 2009)for the development rock and analyzing the filtrate from the two tailings samples by ICP-MS. Solid phase elemental analysis was done to determine the total amount of 51 elements present in the sample solids. Analytical method was aqua regia digestion followed by iCP-MS analysis. Typically,the decision to initiate long term metal release tests is made based on the results from the static testing results. However,given the Dawson project time frame and that the finer grain size of tailings makes them a higher probability source of long term metal release,kinetic testing on tailings began concurrently with the static testing. Long term metal release from tailings was assessed by humidity cell testing following ASTM D 5744—07 (April 2010). Humidity cells were run for twenty-five weeks, at which time parameter concentrations demonstrated a steady state. Development rock did not undergo long term leach testing based on the results of the static testing. A note on the testing methodology used for assessing the short term metal release from development rock. The State of Colorado requests the use of the Synthetic Precipitation Leaching Procedure(SPLP). This test is conducted at 1 part solid sample to 20 parts water. This ratio can dilute soluble metals to the extent that they are below the method detection limit for water analysis, particularly for rock samples with low metal content(such as the development rock samples). The shake flask extraction test is done using 1 part solid sample to 3 parts water. At this ratio soluble metals are more likely to be concentrated enough to be detected,yet dilute enough to avoid hitting solubility limits. To increase the probability of detecting metals,the shake flask extraction procedure was used to test short term metal release from development rock. 2.2 Samples Samples were selected by Zephyr Minerals geologists from drill core retrieved from the Fall 2020 drilling program. Sample sources and descriptions are summarized in Table 1 below. DDS/dds Zephyr Dawson_Tailings Charecteizetion_FinaLReport,Feb.3,22,1:18 PM Feb 2022