Gemstone - Crystal Structure/天然石の結構

March 14, 2017

In order to identify your gems or not, you have to understand the crystal structure.

 

What is Crystal Structure ?

In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material.

 

All gemstone are naturally formed in different ways as mentioned in Gemstone Origin. Gemstones may be formed in single or multiple discrete crystals (such as diamond), in massive collections of microscopic crystals (such as chalcedony), or in amorphous (non-crystalline) masses (such as opal).

 

In General, there are 6 crystal families(Cubic, Tetragonal, Hexagonal, Triclinic, Monoclinic, Orthorhombic) and 7 crystal structure. And each crystal structure have their own number of axes, symmetric 

1. Cubic Family - Isometric Crystal System / Cubic Crystal System

Features of Cubic System

  • 3 axes of equal length and mutually perpendicular to each other

  • 13 symmetric axis

  • 9 plane of symmetry

  • 1 centre of symmetry

  • tetrahedron (4 face) , cube (6 face), the dodecadehedron (12 faces), the trapezohedron (24 faces), and the hexoctahedron (48 faces)

  • Gemstone: diamond, the garnets, pyrite, and spinel

2. Tetragonal Family - Tetragonal System

Features of Tetragonal Crystal System

  • 3 axes intersecting at 90 degree angles, 2 of which are of equal length

  • 5 sysmetric axis

  • 5 plane of symmetry

  • 1 centre of symmetry

  • Gemstone: zircon, rutile, and scapolite.

3. Hexagonal Family -  3.1Hexagonal / 3.2 Trigonal Crystal System

Features of Hexagonal/Trigonal Crystal System

  • have 4 axes, 3 of which are of equal length and intersect at 60 degree angles within a plane, and the 4th of which is perpendicular to the plane of the other three

  •  

  • 7 symmetric axis for hexagonal / 3 symmetric axis for trigonal

  • 7 plane of symmetry for hexagonal / 3 plane of symmetry for trigonal

  • 1 centre of symmetry

  • Gemstone: Trigonal (Corundum/Sapphire/Ruby/Tourmaline/Quartz/Agate/Jasper/Chalcedony/Rhodochrosite) / Hexagonal - Beryl/Morganite/Heliodor/Aquamarine/Emerald

    Trigonal / Hexgonal : Tiger's Eye

4. Triclinic Family - Triclinic Crystal System

Features of Triclinic Crystal System

  • Triclinic system have 3 axes, all of unequal length and intersecting at angles other than 90 degrees

  • 0 sysmetric axis

  • 0 plane of symmetry

  • 1 centre of symmetry

  • Gemstone: labradorite/turquoise/Rhodonite/Amazonite/Sunstone

5. Monoclinic Family - Monoclinic System

Features of Monoclinic Crystal System

  • Monoclinic system have 3 axes of unequal length, 2 of which intersect at an angle other than 90 degrees, and both perpendicular to the third

  • 1 sysmetric axis

  • 1 plane of symmetry

  • 1 centre of symmetry

  • Gemstone: Jadeite /nephrite/Hiddenite/Kunzite/Moonstone/Sodalite/Chrysocolla/Iolite

6.Orthorhombic Family - Orthorhombic Crystal System

Features of Orthorhombic Crystal System

  • Orthorhombic system have 3 axes of unequal length, 3 of them are perpendicular to each order

  • 3 sysmetric axis

  • 3 plane of symmetry

  • 1 centre of symmetry

  • Gemstone: Topaz /Peridot/ Alexandrite /Cat-Eye/Tanzanite/Prehnite

     

     

 

 

 

 

 

 

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