AY Honors/Sand/Answer Key

2008-05-05T20:08:38Z

87.8.87.239: add it:Frattura (mineralogia)

{{dablink|This article is about the terminology used to describe fracture surfaces. For fractures in rocks and minerals ''per se'', see [[Fracture (geology)]]}}

In the field of [[mineralogy]], '''fracture''' is a term used to describe the shape and texture of the surface formed when a [[mineral]] is broken. Minerals often have a highly distinctive fracture, making it a principal feature used in their identification.

Fracture differs from [[Cleavage (geology)|cleavage]] in that that the latter involves clean splitting along the [[Cleavage (crystal)|cleavage planes]] of the mineral's crystal structure, as opposed to more general breakage. All minerals exhibit fracture, but when very strong cleavage is present, it can be difficult to see.

==Terminology==

====Conchoidal fracture====
[[Image:ObsidianOregon.jpg|thumb|left|180px|[[Obsidian]]]]
'''[[Conchoidal fracture]]''' is a curved breakage that resembles the concentric ripples of a [[mussel]] shell. It often occurs in amorphous or fine-grained minerals such as [[flint]], [[opal]] or [[obsidian]], but may also occur in crystalline minerals such as [[quartz]]. '''Subconchoidal fracture''' is similar to conchoidal fracture, but not as curved.
 

====Earthy fracture====
[[Image:Limonite_bog_iron_cm02.jpg|thumb|left|180px|[[Limonite]]]]
'''Earthy fracture''' is reminiscent of freshly broken [[soil]]. It is frequently seen in relatively soft, loosely bound minerals, such as [[limonite]], [[kaolinite]] and [[aluminite]].
 

====Hackly fracture====
[[Image:Cuivre_natif1_%28USA%29.jpg|thumb|left|180px|[[Native copper]]]]
'''Hackly fracture''' (also known as '''jagged fracture''') is jagged, sharp and uneven. It occurs when metals are torn, and so is often encountered in [[native metal|native metals]] such as [[Native copper|copper]] and [[silver]].
 

====Splintery fracture====
[[Image:Chrysotile_1.jpg|thumb|left|180px|[[Chrysotile]]]]
'''Splintery fracture''' comprises sharp elongated points. It is particularly seen in fibrous minerals such as [[chrysotile]], but may also occur in non-fibrous minerals such as [[kyanite]].
 

====Uneven fracture====
[[Image:MagnetitaEZ.jpg|thumb|left|180px|[[Magnetite]]]]
'''Uneven fracture''' is self descriptive. It occurs in a wide range of minerals including [[arsenopyrite]], [[pyrite]] and [[magnetite]].
 

==See also==
*[[Fracture]]
*[[Fracture (geology)]]
*[[Conchoidal fracture]]

==References==
* Rudolf Duda and Lubos Rejl: ''Minerals of the World'' (Arch Cape Press, 1990)
* http://www.galleries.com/minerals/property/fracture.htm

{{Template: Mineral identification}}

[[it:Frattura (mineralogia)]]
[[ru:Излом]]

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AY Honors/Sand/Answer Key