Crack

A crack (also fissure, fault, joint) is an individual fissure, clearly visible by the naked eye, resulting from separation of one part from another.

Cracks in stone
Sub-types of cracks ocuring in stone include:
 * Fractures: Cracks that crosses completely the stone piece
 * Star cracks: Crack having the form of a star. Rusting iron or mechanical impact are possible causes of this type of damage.
 * Hair crack: Minor crack with width dimension < 0.1 mm
 * Craquele: Network of minor cracks also called crack network . The term crazing is generally not considered appropriate for stone, as this term is more commonly used for describing the development of a crack network on glazed terracotta.
 * Splitting : Fracturing of a stone along planes of weakness such as microcracks or clay/silt layers, in case where the structural elements are orientated vertically. For instance, a column may split into several parts along bedding planes if the load above it is too high.

In stone deterioration, cracks should not be confused with delamination, which consists of detachment along bedding or schistosity planes, not necessarily orientated vertically. In delamination, mechanical overload is not noticeable. Delamination is transitional to splitting.

Cracking may be due to weathering, flaws in the stone, static problems, rusting dowels, too hard repointing mortar. Vibrations caused by earth tremors, fire, frost may also induce cracking. Cracks and fractures occuring on rock carved surfaces are usually named after the geological terminology: joint if there is no displacement of one side with respect to the other, fault if there is a displacement.