Glass bead with minimized amount (11 mg) of sample for X‐ray fluorescence determination of archaeological ceramics

By using very small amount – 11‐mg – of sample powder, major oxides (Na 2 O, MgO, Al 2 O 3 , SiO 2 , P 2 O 5 , K 2 O, CaO, TiO 2 , MnO, and total Fe 2 O 3 ) in ancient pottery (and igneous rocks) were determined with X‐ray fluorescence spectrometry. This minimized amount of sample was used to prepare a fused glass bead with 300 times the weight of lithium tetraborate as an alkali flux. Calibration standards were obtained by compounding chemical reagents (Na 2 CO 3 , MgO, Al 2 O 3 , SiO 2 , Na 4 P 2 O 7 , K 2 CO 3 , CaCO 3 , TiO 2 , MnO 2 , and Fe 2 O 3 ) and the flux. Fewer 11 mg of reagents as oxides were able to give reliable calibration curves with good linearity (correlation coefficient: r > 0.995). Fewer 11 mg of sample was able to give reliable analytical results with good precision (relative standard deviation: <3% for more than 10.0 mass% of analyte, <10% for 1.0–10.0 mass% of analyte, and <20% for 0.1–1.0 mass% of analyte). Lower limits of detection were roughly a sub‐percentage of analyte in an unprepared sample (e.g. 0.3 mass% for Na 2 O, 0.5 mass% for MgO, 1.0 mass% for Al 2 O 3 , and 0.01 mass% for MnO). Composition of major oxides in artificial and natural aluminosilicate materials (including rock, stone, sand, sediment, and clay; and their products) should be fundamental information to be considered in detail. The present X‐ray determination based on very small amount of sample might be made readily accessible for destructive analysis of precious samples for archaeology (and geochemistry).