Different results for QGST_BERT_HP and Shielding physics list

Hi,
I have simulated depth-dose profiles for different concrete materials using QGST_BERT_HP and Shielding physics lists. I can’t explain why it showed a sharp difference for Ilmenite (I-Ia )composition and Serpentine(Ser). Can anyone suggest any explanation? The neutron energy is 18.5 MeV. Thanks in advance