Table 6: Chemical compositions of chert samples, named Trd 1-2 and Trd 1-5, representative of the two mineralogical compositions identified (XRF data; LOI: loss on ignition). Note that Ga, Y, Nb, La, Ce, and U contents are not reported because they are lower than XRF detection limits for all samples (LOD of Ga = 5 ppm; LOD of Y, Nb and U = 3 ppm; LOD of La and Ce = 10 ppm).

SampleSiO2TiO2Al2O3Fe2O3MnOMgOCaONa2OK2OP2O5LOIScVCrCoNiCuZnRbSrZrBaNdPbTh
NumberWt%Wt%Wt%Wt%Wt%Wt%Wt%Wt%Wt%Wt%Wt%ppmppmppmppmppmppmppmppmppmppmppmppmppmppm

Trd 1-290.680.010.217.130.150.370.120.050.010.022.18931450712414618467892019127
Trd 1-599.98<0.005<0.02<0.005<0.005<0.02<0.005<0.02<0.005<0.0050.00<3<3<3<3<3<3<3<3<3<3<10<10<10<3