Monoclinic crystal system

In the monoclinic system all the axes are different lengths. Two of them, the A and the C axes, meet at 90 degrees but the third one does not.

This crystal system has the following forms:

  • 3 Pinacoids
  • Prism and 2 Pinacoids
  • Prism and 3 Pinacoids
  • Prism and 5 Pinacoids
monoclinic simple lattice diagram showing axes

The monoclinic simple lattice

monoclinic simple lattice diagram highlighting ends

Pinacoid: A pinacoid is composed of only two parallel faces. In this case, the top and bottom face are the pinacoid forms (the blue faces). There are a total of three pinacoids in this form.

Epidote

Epidote: monoclinic crystal system with 2 pinacoids

Close-up of epidote crystals allowing for more evident geometic recognition

Close-up of epidote crystals

3 pieces of Augite

Augite: monoclinic system prism with 3 pinacoids

Augite close-up

Close-up of augite

Orthoclase

Orthoclase: monoclinic system prism with 3 pinacoids

Gypsum

Gypsum: monoclinic system prism with 5 pinacoids

monoclinic simple lattice diagram showing axes
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The monoclinic simple lattice
monoclinic simple lattice diagram highlighting ends
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Pinacoid: A pinacoid is composed of only two parallel faces. In this case, the top and bottom face are the pinacoid forms (the blue faces). There are a total of three pinacoids in this form.
Epidote
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Epidote: monoclinic crystal system with 2 pinacoids
Close-up of epidote crystals allowing for more evident geometic recognition
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Close-up of epidote crystals
3 pieces of Augite
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Augite: monoclinic system prism with 3 pinacoids
Augite close-up
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Close-up of augite
Orthoclase
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Orthoclase: monoclinic system prism with 3 pinacoids
Gypsum
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Gypsum: monoclinic system prism with 5 pinacoids

Diagrams originally from http://library.thinkquest.org/C005277/Crystal.html