SRMP Dynamic Earth Curriculum - American Museum of Natural ...

Science Research Mentoring ProgramDynamic EarthSession Ten: VolcanismWORKSHEET: Volcanic Rock IdentificationYou will determine a rock type by comparing the chemical abundances in an unknown rock tovalues of known rocks. You’ll look at the percent weights and parts per million (ppm) of severalelements.Suppose you have a collection of 5 rocks that were labeled and stored together on a shelf, alongwith tables of their chemical compositions. The labels have been eaten by mice, but the tables ofchemical composition, which were recorded on less tasty paper, remain. You’re asked to identify therock type for each specimen, and, if possible, where it came from.Table 1: Composition by Percent-WeightFe 2 O 3SiO 2 TiO 2 Al 2 O 3 (T) MnO MgO CaO Na 2 O K 2 O P 2 O 5 Cr 2 O 3 NiO Totalwtwt-%wt-% wt-% wt-% wt-% wt-% wt-% wt-% % wt-% wt-% wt-% wt-%1 48.96 0.43 15.60 9.69 0.16 10.83 13.24 1.30 0.09 0.02 100.322 46.74 2.77 15.35 12.85 0.17 6.80 12.81 2.77 0.80 0.39 0.00 0.00 101.453 48.16 1.06 16.79 10.97 0.19 8.60 11.66 2.28 0.17 0.114 51.23 1.55 17.45 9.59 0.15 6.17 9.38 3.62 0.65 0.20 99.995 49.81 1.91 14.59 11.53 7.48 11.63 2.62 0.13 0.19 99.89Table 2: Composition by ppmTi Rb Sr Y Zr Nb La Ce Nd Sm Eu Tb Yb LuPpm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm1 2577.14 4.00 103.00 9.00 27.00 0.21 0.78 2.13 2.39 0.86 0.36 0.21 1.01 0.162 16628.78 14.00 498.00 23.00 173.00 44.00 28.20 57.80 31.10 6.65 2.19 1.03 1.90 0.293 6352.94 4.00 189.00 57.00 70.00 51.00 7.00 13.50 2.60 0.90 1.704 9289.68 15.00 363.00 27.00 139.00 11.00 10.20 25.00 4.02 1.32 0.77 2.41 0.385 11447.28 0.79 124.50 49.34 162.20 4.41 5.42 17.41 15.23 5.33 1.80 1.23 4.76 0.68© 2013 American Museum of Natural History. All Rights Reserved. 44