Difference between revisions of "Cleavage"

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{{edit|--[[User:Doos|Doos]] 07:20, 9 December 2006 (PST)}}
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==Cleavage==
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Cleavage is the splitting of a gemstone along the direction of its crystal faces where molucules have weak bonding. This can occur only in crystalline minerals when a precise blow is given in a particular direction, even if the habit does not show the crystal faces. The result of cleavage is a more or less flat plane with often a silky luster.<br />
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There are several directions of cleavage.
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* Prismatic cleavage
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* Basal cleavage
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* Pinacoidal cleavage
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* Octahedral cleavage
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* Rhombohedral cleavage
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The quality of cleavage is expressed with a few simple phrases.
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* Perfect
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* Good
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* Fair
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* Poor
  
 
[[image:cleavage_prismatic.jpg|left|thumb|200px|Prismatic cleavage]]
 
[[image:cleavage_prismatic.jpg|left|thumb|200px|Prismatic cleavage]]
 
[[image:cleavage_basal.jpg|left|thumb|200px|Basal cleavage]]
 
[[image:cleavage_basal.jpg|left|thumb|200px|Basal cleavage]]
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<br clear="all" />
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==Parting==
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Parting is the splitting of a gemstone along twinning planes.
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==Fracture==
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Fracture is the random breakage of a gemstone when behing hit with a sharp or hard object. The most common type of fracture is termed "conchoidal" (shell-like).<br />
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The types of fracture are:
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* conchoidal
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* uneven
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* even

Revision as of 14:49, 9 December 2006


Cleavage

Cleavage is the splitting of a gemstone along the direction of its crystal faces where molucules have weak bonding. This can occur only in crystalline minerals when a precise blow is given in a particular direction, even if the habit does not show the crystal faces. The result of cleavage is a more or less flat plane with often a silky luster.

There are several directions of cleavage.

  • Prismatic cleavage
  • Basal cleavage
  • Pinacoidal cleavage
  • Octahedral cleavage
  • Rhombohedral cleavage

The quality of cleavage is expressed with a few simple phrases.

  • Perfect
  • Good
  • Fair
  • Poor
Prismatic cleavage
Basal cleavage


Parting

Parting is the splitting of a gemstone along twinning planes.

Fracture

Fracture is the random breakage of a gemstone when behing hit with a sharp or hard object. The most common type of fracture is termed "conchoidal" (shell-like).

The types of fracture are:

  • conchoidal
  • uneven
  • even