<|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:
4.9 4.9 4.0
90 90 90
Ca
0.73 0.75 0.99
Ca
0.73 0.25 0.99
Ir
0.00 0.00 0.00
Pb
0.46 0.00 0.00
Identify the crystal system.<|im_end|>
<|im_start|>assistant
Given the following crystal representation:
4.9 4.9 4.0
90 90 90
Ca
0.73 0.75 0.99
Ca
0.73 0.25 0.99
Ir
0.00 0.00 0.00
Pb
0.46 0.00 0.00
Identify the crystal system.