Ls. De Jong et Jv. Owen, Reproducibility of electron-microprobe bulk analyses of fine-grained media: A case study using modern bone china, CAN MINERAL, 37, 1999, pp. 239-246
The reproducibility of data on the bulk composition of very fine-grained me
dia, and specifically the concentration of the major elements as establishe
d by electron-microprobe analysis, have been statistically assessed in orde
r to establish criteria for analysis. Two sets of spot analyses, one using
a beam diameter of 20 mu m, the other of 40 mu m, were undertaken on each o
f three fragments cut from a sample of modern bone china. Student's t-tests
were run to determine if there was a significant difference (at 95% precis
ion) between the two datasets. The results show that as few as 35 spot anal
yses need be averaged to provide a reliable indication of bulk composition,
provided that the beam diameter is at least as large as the coarsest grain
s, and much larger than the average grain-size of the medium being analyzed
.