pseudomonoclinic

[Marquetta]

Pseudo-monoclinic refers to a crystal structure that has both monoclinic and triclinic symmetry, which means that the crystal can rotate and twist along its axis, but it cannot tilt or change the angle of its faces. This is in contrast to a monoclinic crystal, which can tilt and rotate but not twist or change the angle of its faces.

A good example to illustrate this concept is the mineral calcite, which has both monoclinic and triclinic symmetry. However, if we break up the crystal into smaller pieces and look at them individually, we can see that each piece has a different angle and twist along its axis, indicating that it is not truly pseudo-monoclinic.

In summary, pseudo-monoclinic refers to a crystal structure that has both monoclinic and triclinic symmetry, but it is not a true monoclinic crystal.