Oxide - Carbonate - Element Conversion TableUpdated 13 November 2021The following table is used when weight based analytical results need to be converted. For example 56.0% CaO might be obtained during a microprobe calcite analysis. The sample is likely to be a carbonate. To convert the oxide to carbonate look at the table below. Find the conversion for CaO and CaCO3 and use the multiplying factor beside CaCO3. The result is 56.0 x 1.7848 = 99.94% CaCO3. A factor is the sum of the atomic weights of the elements in the required formula divided by the sum of the atomic weights in the original formula. For example the factor to convert Fe2O3 to 2FeO is 2 x (55.85 + 16)/(55.85 x 2 + 16 x 3) = 0.8998 while the factor to convert 2FeO to Fe2O3 is 1/0.8998 = 1.1113. An example was recently sent to me which was correct, but there was some uncertainty. An electron microprobe result was Na2O = 0.035%. What would the result be for Na in ppm?
Using the table factors:
It would probably help to round the numbers to be comparable to the precision of the original data. A check calculation is always useful.
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![]() JEPSPECTRO - Home Page Email: replace at with @ jepattersonatactrix.co.nz SGEES Home Page Victoria University JEOL 733 Electron Microprobe Related Links Athena: Mineral Search Mineralogy Database Electron Microprobe Operation Electron Microprobe Standards Atomic WeightsHydrogen 1.01Carbon 12.01 Nitrogen 14.01 Oxygen 16.00 Fluorine 19.00 Sodium 22.99 Magnesium 24.31 Aluminium 26.98 Silicon 28.09 Phosphorous 30.97 Sulphur 32.06 Chlorine 35.45 Potassium 39.10 Calcium 40.08 Titanium 47.90 Chromium 52.00 Manganese 54.94 Iron 55.85 Cobalt 58.93 Nickel 58.71 Copper 63.54 Zinc 65.37 Molecular WeightsAl2O3 101.96CO2 44.01 CaO 56.08 CoO 74.93 Cr2O3 151.99 CuO 79.55 FeO 71.85 Fe2O3 159.69 K2O 94.20 MgO 40.30 MnO 70.94 MnO2 86.94 Mn3O4 228.81 Na2O 61.98 NiO 74.69 P2O5141.94 SO3 80.06 SiO2 60.08 SrO 103.62 TiO2 79.88 ZnO 81.38 |