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.
Table
Fracture
Fracture Description
Brittle - Conchoidal
Very brittle fracture producing small, conchoidal fragments.
Brittle - Irregular
Very brittle fracture producing irregular fragments
Brittle - Subconchoidal
Brittle fracture with subconchoidal fragments
Brittle - Splintery
Brittle fracture leaving splintery fragments.
Brittle - Sectile
Brittle fracture with slightly sectile shavings possible.
Brittle
Generally displayed by glasses and most non-metallic minerals.
Brittle - Uneven
Very brittle fracture producing uneven fragments.
Conchoidal
Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Conchoidal - Irregular
Irregular fracture producing small, conchoidal fragments.
Conchoidal - Uneven
Uneven fracture producing small, conchoidal fragments.
Elastic
Fragments which spring back after bending.
Earthy
Dull, clay-like fractures with no visible crystalline affinities, (e.g. howlite).
Even
Flat surfaces (not cleavage) fractured in an even pattern.
Fibrous
Thin, elongated fractures produced by crystal forms or intersecting cleavages (e.g. asbestos).
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, (e.g. granite).
Hackly
Jagged, torn surfaces, (e.g. fractured metals).
Irregular
Flat surfaces (not cleavage) fractured in an irregular pattern.
Micaceous
Fracture of flexable micaceous cleavage fragments.
Malleable
Deforms rather than breaking apart with a hammer.
None
No fractures
Plastic
Deforms like soft, plastic materials.
Plastic - Splintery
Thin, soft flexable, elongated fractures produced by intersecting good cleavages or partings (e.g. hornblende).
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, (e.g. graphite).
Splintery
Thin, elongated fractures produced by intersecting good cleavages or partings (e.g. hornblende).
Sugary
Fracture surfaces produced by finely aggregated minerals, (e.g. massive anhydrite).
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.
Example Subject Searches
Example: "fracture splintery"" for all minerals with a splintery fracture.
Example: "fracture tough" for all minerals with a noticeably tough (hard to break) tenacity
