0.06 0.32 0.23 0.27 0.17 P2O5 0.08 0.10 0.35 0.42 1.97 LOI (1) Calculate Mg# assuming FeO (total) is all Fe2+ 61.76 Mg# (2) Recalculate FeO and Fe2O3 assuming that Fe2O3 is equal to 25 percent of FeO total Fe2O3 3.06 FeO 8.25 (3) Recalculate Mg# using recalculated FeO 68.29 Mg# Is sample likely to be primitive yes mantle melt (Mg# > 65)? Exercise 3. Calculating normative mineralogies Calculate the normative mineralogy for each of the samples in the table below using either the spreadsheet from , or by making your own spreadsheet to complete the calculations. Assume Fe 3+ = 25% of the total reported Fe. Oxide (wt. %) CN-4 CN-6 IL-4 IL-5 IL-1 48.6 50.4 58.21 66.8 70.6 SiO2 0.65 0.83 0.66 0.4 0.25 TiO2 14.4 20.0 17.6 15.7 14.9 Al2O3 11.0 9.6 6.45 3.76 2.00 FeO (total) 0.2 0.18 0.14 0.08 0.12 MnO 9.97 3.69 3.34 1.5 0.68 MgO 11.3 11.4 7.62 4.17 2.89 CaO 1.78 2.38 3.43 4.28 4.14 Na2O 0.35 0.47 1.12 1.99 2.3 K2O 0.06 0.32 0.23 0.27 0.17 P2O5 0.08 0.10 0.35 0.42 1.97 LOI Total Recalculated Fe2O3 and FeO (remember that Fe2O3 = FeO/0.9)
P2O5 0.06 0.32 0.23 0.27 0.17 LOI 0.08 0.10 0.35 0.42 1.97 (1) Calculate Mg# assuming FeO (total) is all Fe2+ Mg# 61.76 (2) Recalculate FeO and Fe2O3 assuming that Fe2O3 is equal to 25 percent of FeO total Fe2O3 3.06 FeO 8.25 (3) Recalculate Mg# using recalculated FeO Mg# 68.29 Is sample likely to be primitive mantle melt (Mg# > 65)? yes Exercise 3. Calculating normative mineralogies Calculate the normative mineralogy for each of the samples in the table below using either the spreadsheet from , or by making your own spreadsheet to complete the calculations. Assume Fe 3+ = 25% of the total reported Fe. Oxide (wt. %) CN-4 CN-6 IL-4 IL-5 IL-1 SiO2 48.6 50.4 58.21 66.8 70.6 TiO2 0.65 0.83 0.66 0.4 0.25 Al2O3 14.4 20.0 17.6 15.7 14.9 FeO (total) 11.0 9.6 6.45 3.76 2.00 MnO 0.2 0.18 0.14 0.08 0.12 MgO 9.97 3.69 3.34 1.5 0.68 CaO 11.3 11.4 7.62 4.17 2.89 Na2O 1.78 2.38 3.43 4.28 4.14 K2O 0.35 0.47 1.12 1.99 2.3 P2O5 0.06 0.32 0.23 0.27 0.17 LOI 0.08 0.10 0.35 0.42 1.97 Total Recalculated Fe2O3 and FeO (remember that Fe2O3 = FeO/0.9)
handout03_lavascentralamerica_.v5.docx