天然晶体 meaning in Chinese

mineral crystal
natural crystal

But the normal iceland crystal is a nature crystal and transparent . it is not easy to find pure and big iceland crystal , so it is difficult to make large - size polarizing device . at the same time , the process is complex and with high price
但由于通常使用的冰洲石晶体是一种天然晶体，纯净的晶体很少，且不易得到大块，所以晶体起偏镜不容易做成大口径，且价格高，加工工艺复杂。