www.rpacan.com FIGURE 12-1 ANALYSES OF TOTAL RARE EARTH ELEMENTS, ACME VS ALS FIGURE 12-2 ANALYSES OF TOTAL HEAVY RARE EARTH ELEMENTS, ACME VS ALS Avalon Rare Metals Inc. – Thor Lake Project, Project #1714 Technical Report NI 43-101 – August 22, 2011 Rev. 0 Page 12-6 www.rpacan.com TABLE 12-4 COMPARISON OF NIOBIUM, TANTALUM AND ZIRCONIUM ANALYSES Avalon Rare Metals Inc. – Thor Lake Project Standard Lab Method No. Nb (%) Ta (%) Zr (%) STD-L ALS MS81 188 100 99 101 STD-L ALS MS81H 19 101 100 101 STD-L Acme Method 4A 98 103 91 103 STD-L ALS XRF 43 104 73 106 Average (ppm) 1,383 144 9,750 STD-M ALS MS81 153 103 98 66 STD-M ALS MS81H 87 101 96 95 STD-M Acme Method 4A 121 109 90 106 STD-M ALS XRF 46 109 88 115 Average (ppm) 2,196 227 14,087 STD-H ALS MS81 112 100 100 66 STD-H ALS MS81H 99 98 96 111 STD-H Acme Method 4A 224 98 95 111 STD-H ALS XRF 21 98 98 120 Average (ppm) 2,676 301 17,234 STD-H2 ALS MS81 285 96 36 29 STD-H2 ALS MS81H 182 95 124 100 STD-H2 Acme Method 4A 38 93 99 80 STD-H2 ALS XRF 220 94 124 100 Average (ppm) 4,132 313 34,323 Note: Cases with analytical limits removed The results indicate the following: • For the low grade standard (STD-L), all methods (Acme and ALS) give similar results for Nb and Zr, but XRF appears to give anomalously low results for Ta. The cause of this is not known. Standard STD-M is similar. • For higher grade Zr samples (>1%), MS81 does not give correct results due to analysis upper limits, however, for Nb and Ta (with the exception of standard H2/S-04-09) the results are satisfactory. • Except for standard H2/S-04-09, Zr values are 6% to 20% higher with XRF than the average of all analyses from all labs. In addition, XRF10 analyses generally show very low standard deviations. It is concluded that zirconium analyses are systematically higher with XRF, and that these may in fact be more representative of the Zr content of the rock. On the other hand, the Nb and Ta analyses by ICP methods (ALS MS81H and Acme 4A/4B) are all sufficiently close that it is not necessary to conduct additional XRF analyses of these Avalon Rare Metals Inc. – Thor Lake Project, Project #1714 Technical Report NI 43-101 – August 22, 2011 Rev. 0 Page 12-7 www.rpacan.com elements. Given the important of Zr to the overall economics of the deposit, drill core should be routinely analyzed by XRF methods for Zr as otherwise the ZrO2 grade may be systematically understated in resource estimates. Avalon monitors the results of the Company’s internal standards during routine analysis of drill core. Due to the large number of elements involved, being fifteen rare earth elements and three rare metals (Nb, Ta, Zr), it would be impractical to apply a normal logic table of failures where an analysis batch is failed on the basis of issues with one element. In addition, all core is analyzed and so about two-thirds of the samples that have chemical data are not significant in terms of the economics of the deposit. As a result, Avalon followed the following procedure for assessing analytical data: • Batches were not failed if the samples analyzed were clearly far below any economic levels (not mineralized), unless the standards results were very grossly out. • The results of the standards were reviewed to see how many elements were out of acceptable range as recommended in the standard certification, and if four elements were out of range (greater than three standard deviations), but two high and two low, and the remaining 14 elements were in range, the batch was accepted. • If five elements or more elements were out of acceptable range (greater than three standard deviations), and all in the same direction, either biased all high or all low, then the batch was re-analyzed. There were a few cases of blanks being out of acceptable range. However, on close examination of the results, these were almost invariably clearly associated with sample switching, and it was clear that a mineralized sample and the blank had been switched. There was a noticeable reduction in the number of cases of standards being out of range in the case of ALS method MS81H compared to MS81. The overall conclusions of the QA/QC work completed are as follows: • Standard deviations of duplicate analyses on standards indicate that the precision of the laboratories is satisfactory, both for ALS Laboratory and Acme Laboratory. • Duplicate analyses of standards and the duplicate reject analyses indicate that there is little systematic bias between ALS Laboratory and Acme Laboratory. • ALS Laboratory and Acme Laboratory indicate means for the four standards utilized by Avalon within 5% of the accepted values for most rare earth elements, Avalon Rare Metals Inc. – Thor Lake Project, Project #1714 Technical Report NI 43-101 – August 22, 2011 Rev. 0 Page 12-8 www.rpacan.com Nb and Ta. Zr shows more deviation, with ALS MS81H and Acme Method 4A/4B being higher, as are the XRF analyses completed at ALS. • Although there may be systematic differences between ALS and Acme for individual rare earths, in general, the TREE and HREE indicate that this difference is about 1% for TREE and 1.5% for HREE. • Given the general agreement between laboratories on the mean of the standards, and the low standard deviation of duplicate analyses, Avalon considers that the standards are acceptable for QA/QC monitoring of the drill core analyses. • In conclusion, the drill core analyses are considered sufficiently reliable for resource estimation purposes, with the caveat that analyses for Zr require further investigation to establish the cause of the difference between the various methods. • However, Avalon does not consider that the variation in Zr analyses is material to the resource given the low proportion of the total value of Zr relative to all other metals (rare earths, Nb and Ta). SPECIFIC GRAVITY MEASUREMENT A detailed description of the routine used for specific gravity data collection is given in Section 11. INDEPENDENT SAMPLING BY RPA During the April 2011 site visit, RPA personnel collected eight core samples from six diamond drill holes from the 2010 drill program. Six of the samples were from the Basal Zone, and two from the Upper Zone. The core samples consisted of the second half core or quartered core retained by Avalon. The samples were processed at SGS Toronto using the IMS95A and the IMS91B analytical packages. The presence of mineralization was confirmed and the assay results are similar to the original samples. It is the opinion of RPA that Avalon follows the current industry practice, and that the analysis of standards, blanks, and duplicate reject samples show acceptable results. Avalon Rare Metals Inc. – Thor Lake Project, Project #1714 Technical Report NI 43-101 – August 22, 2011 Rev. 0 Page 12-9 www.rpacan.com 13 MINERAL PROCESSING AND METALLURGICAL TESTING METALLURGICAL TESTING Numerous metallurgical tests have been conducted over the last two years to determine how best to recover the valuable elements from Thor Lake Basal Zone ore. The results of these tests and brief economic trade-off studies have led to the selection of a process including grinding, froth flotation, decomposition of the refractory rare earth, zirconium, and niobium-tantalum minerals and recovery of these elements from solution by solvent extraction and precipitation methods. Metallurgical tests were undertaken on representative samples, both geographically and geologically, of the Upper and Basal Zones of the deposit, prepared in 2008, 2009 and 2010. The samples were developed from multiple drill holes, with composites comprising of numerous samples across the mineralized zones. MINERALOGY The mineralogy of the mineralized material from the Thor Lake Deposit ore has been detailed in Section 9 of this report. The important minerals are zircon, allanite, monazite, fergusonite, bastnaesite, and synchysite. The minerals of interest are fine-grained and typically in the 5 to 25 µm size range. COMMINUTION Five carefully selected composite samples of Upper Zone (UZ) and Basal Zone (BZ) material and waste rock were prepared and submitted to Starkey and Associates for SAG Design testing and to SGS Lakefield Research Limited for assessment of comminution properties. SGS reported a Bond metric rod mill work index value of 16 kWh/t for a UZ sample and values of 14 kWh/t and 16.5 kWh/t for two BZ samples. The values show rock of average toughness according to the SGS database. SGS measured the abrasion indices at 0.3 to 0.4 g indicating moderately abrasive material. Avalon Rare Metals Inc. – Thor Lake Project, Project #1714 Technical Report NI 43-101 – August 22, 2011 Rev. 0 Page 13-1 www.rpacan.com Bond ball mill work index tests returned metric values of about 15 kWh/t for all samples with very little variation when tested using 75 and 106 µm closing screens. Based on the data, Melis Engineering designed a comminution circuit comprising crushing to -15 mm followed by rod and ball milling to achieve the target grind of 80% passing 38 µm. The SAGDesign tests showed that the ore was amenable to semi-autogenous grinding (SAG) and this option may be examined again in future testwork and design studies. FLOTATION Numerous open circuit and locked cycle flotation tests have been done at SGS by Srdjan Bulatovic of SBM Mineral Processing and Engineering Services Ltd.