| Atomic Coordinates | Indices | ||
| P-3 | |||
| x, y, z | -x, -y, -z | h, k, l | -h,-k, -l |
| -y, x-y, z | y, -x+y, -z | k, -h-k, l | -k, h+k, -l |
| -x+y, -x, z | x-y, x, -z | -h-k, h, l | h+k, -h, -l |
| P-31m | |||
| -y, -x, -z | y, x, z | -k, -h, -l | k, h, l |
| -x+y, y, -z | x-y, -y, z | -h, h+k, -l | h, -h-k, l |
| x, x-y, -z | -x, -x+y, z | h+k, -k, -l | -h-k, k, l |
| P-3m1 | |||
| y, x, -z | -y, -x, z | k, h, -l | -k, -h, l |
| x-y, -y, -z | -x+y, y, z | h, -h-k, -l | -h, h+k, l |
| -x, -x+y, -z | x, x-y, z | -h-k, k, -l | h+k, -k, l |
| P6/m | |||
| -x, -y, z | x, y, -z | -h, -k, l | h, k, -l |
| y, -x+y, z | -y, x-y, -z | -k, h+k, l | k, -h-k, -l |
| x-y, x, z | -x+y, -x, -z | h+k, -h, l | -h-k, h, -l |
Merohedral Twins in the Trigonal/Hexagonal Crystal System
| Laue | Apparent | Indices related | TwinLaw |
| group | Laue Group | by Twinning | |
| -3 | -31m | k, h, l | 0 1 0 1 0 0 0 0 1 |
| -3 | -3m1 | k, h, -l | 0 1 0 1 0 0 0 0 -1 |
| -3 | 6/m | h, k, -l | 1 0 0 0 1 0 0 0 -1 |
| -3 | 6/mmm | k, h, l | 0 1 0 1 0 0 0 0 1 |
| k, h, -l | 0 1 0 1 0 0 0 0 -1 | ||
| h, k, -l | 1 0 0 0 1 0 0 0 -1 | ||
| -3m1 | 6/mmm | h, k, -l | 1 0 0 0 1 0 0 0 -1 |
| -31m | 6/mmm | h, k, -l | 1 0 0 0 1 0 0 0 -1 |
| 6/m | 6/mmm | k, h, -l | 0 1 0 1 0 0 0 0 -1 |