某矿物三个任意切面的折射率为1. N1=1.551, N2=1.544; 2. N1=1.549, N2=1.544; 3. N1=1.553, N2=1.544。该矿物的轴性为______ ，光性符号为______
某矿物三个任意切面的折射率为1. N1=1.551, N2=1.544; 2. N1=1.549, N2=1.544; 3. N1=1.553, N2=1.544。该矿物的轴性为______ ，光性符号为______
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