Mucic acid crystals grown from a water-based solution achieved a record-breaking stiffness for an organic crystal.

Stiffness is often described as the measure of resistance to deformation when a material is subjected to an external force. When we think of a stiff material, metals or ceramics usually come to mind, rather than crystals or organic molecules such as sugar or citric acid.

Hydrogen bonds have the ability to make even famously brittle and hard organic crystals ultrastiff.