Glittering Stones

Glittering Stones » Semi Precious Stones » Tourmaline



Semi Precious Stone Tourmaline


The mineral tourmaline is a complex silicate of aluminium and boron, but because of isomorphous replacements it varies widely in composition with iron, magnesium and lithium also entering into the combination to a greater or lesser extent. Tourmaline belongs to the hexagonal system, with long, slender, prismatic acicular crystals that are usually terminated with three faces of a rhombohedron. The smaller crystals are often found in a radial pattern, and collumnar masses are common. The prisms are usually three, six, or nine sided with heavy vertical striations producing a rounded effect. Tourmaline is essentially without cleavage, its fracture is conchoidal to even, its hardness is 7-7.5, its specific gravity is 2.9-3.2, and it has a vitreous lustre inclining to resinous.


Tourmaline

Historical Facts of Tourmaline

Refractive index

1.635 – 1.675, 1.610 – 1.650

Chemical Composition

(Ca,K,Na)(Al,Fe,Li,Mg,Mn)3 (Al,Cr,Fe,V)6 (BO3)3 (Si,Al,B)6O18 (OH,F)4

Hardness

7 – 7.5

Crystal Group

Hexagonal

Luster

Vitreous, sometimes resinous

Specific gravity

3.06 (+.20 -.06)

Density

2.82–3.32

Color

Blue, green, red, yellow, pink, brown, orangy red, purplish red, black, colorless

Recognized minerals

Buergerite, Chromdravite, Dravite, Elbaite, Feruvite, Foitite, Liddicoatite, Magnesiofoitite, Olenite, Povondraite, Rossmanite, Schorl, Uvite, Vanadiumdravite

Tourmaline species

Dravite species, Schorl Species, Elbaite Species

Tourmaline varieties

Dravite, Brazilian sapphire, schorl, rubellite variety, indicolite, verdelite or Brazilian emerald, achroite

Occurrence

Brazil, Africa, Sri Lanka, Tanzania, Nigeria, Kenya, Madagascar, Mozambique, Namibia, Afghanistan, Pakistan, Malawi

Pleochroism

Red Tourmaline - Definite; dark red, light red
Green Tourmaline - Strong; dark green, yellow-green
Brown Tourmaline - Definite; dark brown, light brown
Blue Tourmaline - Strong; dark blue, light blue

Gem stones Tourmaline

Tourmaline Bracelet

Tourmaline Bracelet

Tourmaline Earring

Tourmaline Earring

Tourmaline Necklace

Tourmaline Necklace

Tourmaline Rings

Tourmaline Ring

 

NOVEMBER BIRTHSTONE - CITRINE


Citrine Gemstone

COMMEMORATIVE EVENT - 13th Anniversary
KEYWORDS - Success, Abundance, Personal Power
ALSO KNOWN AS - Merchant's stone, Success stone
COLORS - Pale yellow to brown
OCCURRENCE - Brazil
COLOR ZONING - Tiger stripes or Zebra stripes

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