Trace-element chemical data of 24 samples (15 faceted
and 9 rough) were measured quantitatively by laser
ablation–inductively coupled plasma–mass spectrometry
(LA-ICP-MS) at the Johannes Guten berg University’s
Institute of Geosciences using an Agilent 7500ce quadrupole
ICP-MS coupled with a New Wave Research
NWR-193 laser ablation system (193 nm wavelength).
Ablation was carried out with helium as the carrier gas
at an energy density of 2.77 J/cm2, a pulse rate of 10 Hz,
and a 50 μm crater size. NIST SRM 610 and 612 glass
reference materials were used as external standards, and