Given:
Intercepts of the plane on crystallographic axes are:
\[ 0.5a : 1b : 0.75c \] Step 1: Convert intercepts to fractional intercepts
\[ x = 0.5,\quad y = 1,\quad z = 0.75 \] Step 2: Take reciprocals to get Miller indices
\[ h = \frac{1}{0.5} = 2,\qquad k = \frac{1}{1} = 1,\qquad l = \frac{1}{0.75} = \frac{4}{3} \] Step 3: Clear fractions by multiplying all by 3
\[ (2,\,1,\,\tfrac{4}{3}) \times 3 = (6,\,3,\,4) \] Thus the Miller index \(l = \boxed{4}\).
| Group I | Group II |
| P. Sillimanite | 1. First order |
| Q. Quartz | 2. Second order |
| R. Muscovite | 3. Greater than third order |
| S. Calcite | 4. Third order variegated |
| Group I | Group II |
| P. Bababudan Group | 1. Eastern Dharwar |
| Q. Banded Gneissic Complex-I | 2. Western Dharwar |
| R. Bonai Granite | 3. Aravalli |
| S. Kolar Group | 4. Singhbhum |