GEOLOGY
CRYSTALLOGRAPHY
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]


(212)


(112)


(211)


(111)

Detailed explanation1: The orthorhombic crystal has axial units in the ratio of 0.424 : 1: 0.367. The miller indices of a crystal face whose intercepts are in the ratio 0.212 :1 :0.183 will be :a)2 : 1 : 2b)1 : 2 : 1c)4 : 1 : 4d)2 : 1 : 1Correct answer is option ‘A’.
Detailed explanation2: By calculation, the miller indices of 2a, 3b, 4c is 6, 4, 3. Hence option 1 is correct.
Detailed explanation3: Miller indices (h, k, l) are expressed as a reciprocal of intercepts p, q, and r made by the plane on the three rectangular axes x, y, and z respectively. where, p = intercept of the plane on the xaxis, q = intercept of the plane on the yaxis, and r = intercept of the plane on the zaxis.
Detailed explanation4: The equation for a plane in three dimensions is exactly analogous for the line in two dimensions: x/a + y/b + z/c = 1. If line OP is perpendicular to the plane, its equation is also analogous to the twodimensional case: xa = yb = zc.
Detailed explanation5: Hence, the miler indices are (122). Hence, the miller indices are (3¯¯¯¯22).