The Precious stones in Sri Lanka

The wealth of natural gems can be divided in to 3 parts minerals, animals, trees. These are again divided in to 2 categories voluble gems and semi voluble gems.

The organic combination such as organic materials and coal are not found from the begging of the earth. These are made with the effecting of organisms (animals and trees) there fore they are not considering as minerals. In hence they are also not gems. As well as there is a structure which had prepared according to the chemical composition as examples for non minerals calcium carbonate (caco3)

Minerals are introduced as the inorganic combinatory with a firm chemical composition and which has a geometric shapes are introduced as minerals.

The specialty of the gems which have been found like this rather than the other minerals consisting of their rarity durability and beauty etc.

These gems are very useful to us they are to emboss the jewel Aries as a medicine of caning diseases, to modify ornaments and gadgets etc.

The value of these will be decided according to their colour, clarity, cut, carat, weigh etc.


The definition of gems
Gem includes a precious stone or a semi precious stone or a product of any gem or any stone.

Crystal system
The crystal system will be taken a special position when recognize the gems among the minerals. Crystal are introduced as the substances which has made according a certain atomic structure and a particular chemical composition

hese have been categorized in to 7 according to their structures.

Cubic system
Applicable gems stone
Diamond grenet

Florite

Tetragonal system

Applicable gems stone

Rutile,Zirocon,Sheelite,Scopolite

Hexagonal system
Applicable gems stone

Trigonal system
Applicable gems stone

Orthorhombic system
Applicable gems stone

Topaz,Iolite,Sinhalite,Peridot,Alexandrite,Andalusite

Monoclinic system

Applicable gems stone
Moon stone,Feldspar,Epidot,Spodumeen,Jadite

Triclinic system
Applicable gems stone
Amosonite,Axinite,Albiteal,Tubauise,Feldspar

Special optical properties of gem
*Luster *sheen
*chatoyuncy (cats eye) *star effect

*aventurescence *Irideseenee

The rare gems found in SriLanka

Apatite
Chemical composition : Ca4 (caf)(po4)2 calcium florid silicate
Crystal system: hexagonal
Hardness : 5
Refractive index : 1.632-1.646
Doubly refraction : 0.002-0.004
Colour : yellowish green, rose, purple, colourless

Andalusite Akanite
Chemical composition : al2sio4 Chemical composition : ca2(th.u)si8o20
Crystal system :orthorhombic Crystal system : tetragonal
Hardness :7.5 Hardness : 6-6.5
Refractive index :1.634-1.644 Refractive index :1.590
Doubly refraction :0.007-0.011 Colour : green
Colour :greenish brown, brownish green, dark green, light green

Fibrolite/ silmanite
Chemizcal composition :al2sio2
Crystal system : orthorhombic
Hardness :7.5
Refractive index :1.659-1.680
Doubly refraction :0.020

Colour :blue, brown, ash

Iolite

Chemical composition :mg(fe)4al(oh)2(si2o7)
Crystal system : orthorhombic
Hardness :7-7.5
Refractive index :1.53-1.54
Doubly refraction :0.008-0.012

Colour :violet,blue

The gems found in Sri Lanka

Zircon
Crystal system : tetragonal
Varieties : yellow, green, brown,
red, orange, blue, golden Zircon
Refractive index : 1.93-1.99
Doubly refraction : 0.002-0.005
Hardness : 7.5
Chemical composition :zirconium silicate

Topaz
Crystal system : orthorhombic
Varieties : sherry, pink, blue, green, orange, brown topaz
Refractive index :1.619-1.627
Doubly refraction : 0.008-0.010
Hardness :8Chemical composition :aluminium fluroydroxy silicate

Garnet family
Crystal system : cubic
Varieties : almandine, pyrop, spessartite
Refractive index :1.72-1.89
Doubly refraction : none
Hardness :6.5-7.5

corundum
Crystal system : tetragonal
Varieties : ruby, sapphire colours
Refractive index :1.718
Doubly refraction : 0.008
Hardness : 9
Chemical composition :AL2O3

Spinel
Crystal system : cubic
Varieties : white, red rubcell, blue topaz, brown
Refractive index : 1.762-1.77.
Hardness :8
Chemical composition :mg al2o3 ( mgoal2o3)]

Tourmaline

Crystal system : tetragonal
Varieties : corome, rubellite, indiolite, verditite, apurite,
achroite, siberite, watermelon, schorl
Refractive index : 1.62-1.64
Doubly refraction : 0.018-0.020
Hardness : 7.5
Chemical composition : complex borosilicate

The gems searched in sri lanka

Baddeleyite Zro2 ,Taaffeite BeMg3AL8O16,Sinhalite mgAlBO4,Ekanite ca2(th.u)si8O20,Serendibite, gem quality 1996,Dunilite – Olivine 1996,Aluminoenstatite 1998,Metamict allanite 1999