GemstonesFinishingBirthstoneGem galleryJewelry
 

 History & Folkare

Optical Properties

Physical Properties

Specific gravity  

Conductivity

 
Crystal systems

Synthetic Gems

 

CRYSTAL SYSTEMS


Although traditionally crystal systems are not part of the physical properties table of gemstones, but most mineral gemstones are crystaline, with thier atoms arranged in regular and symmetrical patterns. Crystal systems are classifed into seven different systems, according to the "minimum symmetry" of their faces.

  • Hexagonal/Trigonal This systems share the same axis of symmetry

  • Monoclinic The monoclinic system has a minimum symmetry of the one two-fold axis.

  • Cubic or Isometric Crystals in the cubic system have the highest symmetry. The minumum symmetry is four-fold axes.

  • Tetragonal This system is defined by one four-fold axis.

  • Orthorhombic The minimum symmetry of this system is three two-fold axis.

  • Triclinic Crystals of this system have no axis of symmetry, so gemstones within this system are the least symmetrical.



IMPORTANT PROPERTIES OF A FEW GEMSTONES

Name

Hardness

Chemical Formula

Density

Crystal

Agate

6.5 - 7

SiO2

2.57 - 2.64

Hexagonal

Alexandrite

8.50

BeAl2O4

3.73

Orthorhombic

Amethyst

7

SiO2

2.66

Hexagonal

Aquamarine

7.5

Be3Al2(SiO3)6

2.67-2.745

Hexagonal

Calcite

3

CaCO3

2.70

Triclinic

Cats Eye

8.5

BeAl2O4

3.73

Orthorhombic

Diamond

10

C

3.52

Cubic

Emerald

7.5-8

Be3Al2(SiO3)6

2.72 (-.05, +.12)

Hexagonal

Fluorite

4

CaF2

3.18

Cubic

Fresh Water Pearls

3.5 - 4.0

CaCO3

2.66 2.78+

Not applicable

Jadeite

7

NaAl(SiO3)2</SUB< SPAN>

3.32

Monoclinic

Mali Garnet

7.25

Ca3Al2(SiO4)3

3.65

Cubic

Moonstone

6 6.50

KalSI3O8

2.55 2.57

Monoclinic

Opal

5.5 - 6.0

SIO2nH2O

2.65 - 3.00

Amorphous

Peridot

6.5

(Mg,Fe)2(SiO)4

3.34

Orthorhombic

Quartz

7

SiO2

2.65

Trigonal

Ruby

9

AL2O3

4.00

Hexagonal

Sapphire

9

AL22O3

4.00

Hexagonal

Spinel

8

MgAl2O4

3.60 (-.03, +.30)

Cubic

Star Sapphire

9

AL2O3

4.00

Hexagonal

Tanzanite

6-7

Ca2(Al,OH)Al2(SIO4)

3.30 (+.10, -.10)

Orthorhombic

Topaz

8

AL(F,OH)2SIO4

3.52 - 3.56

Orthorhombic

Turquoise

5.5-6

CuAl6(PO4)4(OH)85H2O

2.60- 2.90

Triclinic

Natural Gemstones

 

 


 

   
The Rainforest Site
Custom Search

Home Optical Properties History & Folkare Physical Properties Synthetic Gemstones Zodiac stones