<|im_start|>system
Please reason step by step, and put your final answer within \boxed{}.<|im_end|>
<|im_start|>user
Given the following crystal representation:
3.5 3.5 7.7
90 90 90
Ca
0.75 0.75 0.23
Hf
0.00 0.00 0.22
Hf
0.75 0.75 0.47
Si
0.00 0.00 0.27
Identify the crystal system.<|im_end|>
<|im_start|>assistant
Given the following crystal representation:
3.5 3.5 7.7
90 90 90
Ca
0.75 0.75 0.23
Hf
0.00 0.00 0.22
Hf
0.75 0.75 0.47
Si
0.00 0.00 0.27
Identify the crystal system.