Fracture: Tenacity is the resistance that a mineral offers to breaking, crushing, bending, cutting, or other acts of destruction. Fracture is how the mineral breaks once the tenacious limit has been exceeded.

Fracture Type     Fracture Description

Brittle                      Generally displayed by glasses and most non-metallic minerals

Conchoidal              Fractures developed in brittle materials characterized by smoothly curving                                 surfaces

Elastic                      Fragments which spring back after bending
                                   Earthy                      Dull, clay-like fractures with no visible crystalline affinities

                                   Even                        Flat surfaces (not cleavage) fractured in an even pattern

                                   Fibrous                    Thin, elongated fractures produced by crystal forms or intersecting cleavages

                                   Fragile                     Crystals with a delicate and easily injured structure

                                   Flexible                    Flexible fragments

                                   Friable                     The crumbly disintegration of earthy materials or highly fractured minerals

                                   Granular                  Fracture surfaces produced by aggregated minerals

                                   Hackly                      Jagged, torn surfaces, (e.g. fractured metals)

                                   Irregular                  Flat surfaces (not cleavage) fractured in an irregular pattern

                                   Micaceous               Fracture of flexible micaceous cleavage fragments

                                   Malleable                 Deforms rather than breaking apart with a hammer

                                   None                        No fractures

                                   Plastic                      Deforms like soft, plastic materials

                                   Regular                    Flat surfaces (not cleavage) fractured in a regular pattern

                                   Sub Conchoidal       Fractures developed in brittle materials characterized by semi-curving                                                                    surfaces

                                   Sectile                      Curved shavings or scrapings produced by a knife blade

                                   Splintery                   Thin, elongated fractures produced by intersecting good cleavages or                                                                     partings

                                   Sugary                      Fracture surfaces produced by finely aggregated minerals

                                   Tough                      Difficult to break apart as shown by fibrous minerals and most metals

                                   Unknown                  Minerals too small to observe fractures

                                   Uneven                     Flat surfaces (not cleavage) fractured in an uneven pattern

                                   Weak                       Hard to handle without causing serious harm or damage