Home      Discussion      Topics      Dictionary      Almanac
Signup       Login
Jargoon

Jargoon

Discussion
Ask a question about 'Jargoon'
Start a new discussion about 'Jargoon'
Answer questions from other users
Full Discussion Forum
 
Encyclopedia
Jargoon or jargon is name applied by gemologists
Gemology
Gemology or gemmology is the science dealing with natural and artificial gems and gemstones. It is considered a geoscience and a branch of mineralogy...

 to those zircon
Zircon
Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. A common empirical formula showing some of the range of substitution in zircon is 1–x4x–y...

s which are fine enough to be cut as gemstone
Gemstone
A gemstone or gem is a piece of mineral, which, in cut and polished form, is used to make jewelry or other adornments...

s, but are not of the red color which characterizes the hyacinth or jacinth
Jacinth
Jacinth is a red transparent variety of zircon used as a gemstone. Jacinth is also a flower of a reddish blue or deep purple , and hence a precious stone of that colour ....

. The word is related to Arab
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...

 zargun (zircon). Some of the finest jargoons are green, others brown and yellow, whilst some are colorless. The colorless jargoon may be obtained by heating certain colored stones. When zircon is heated it sometimes changes in color, or altogether loses it, and at the same time usually increases in density and brilliancy. The so-called Matura diamonds, formerly sent from Matara (or Matura), in Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

, were decolorized zircons. The zircon has strong refractive power, and its lustre is almost adamantine, but it lacks the fire of the diamond. The specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

 of zircon is subject to considerable variation in different varieties; thus Sir A. H. Church found the specific gravity of a fine leaf-green jargoon to be as low as 3.982, and that of a pure white jargoon as high as 4.705. Jargoon and tourmaline
Tourmaline
Tourmaline is a crystal boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone and the gem comes in a wide variety of colors...

, when cut as gems, are sometimes mistaken for each other, but the specific gravity is distinctive, since that of tourmaline is only 3.103. Moreover, in tourmaline the dichroism
Dichroism
Dichroism has two related but distinct meanings in optics. A dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths , or one in which light rays having different polarizations are absorbed by different amounts.The original meaning of...

 is strongly marked, whereas in jargoon it is remarkably feeble. The refractive indices
Refractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....

of jargoon are much higher than those of tourmaline.