Table 5. µ-XRF results of the investigated crystals M4, M5 and M6 for the first parts of the grown crystals close to the seeds (in p.p.m. by weight).

The composition of a seed crystal (for M6) is shown for comparison. Most of the measured elements are below the detection limit (LOD).

Spectrum	Ca	Ti	V	Cr	Mn	Fe	Zn
Seed for M6	457	9	21	28	11	113	< LOD
M4	11 ± 2	< LOD	< LOD	< LOD	< LOD	< LOD	< LOD
M5	19 ± 1	< LOD	< LOD	< LOD	< LOD	< LOD	< LOD
M6	25	< LOD	< LOD	< LOD	< LOD	< LOD	< LOD