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Zircon
Zircon
is
a genuine gemstone not to be confused with the man-made cubic zirconia.
This gem has a very high birefringence (splits light into two rays) which
makes the back facets appear double when looking through the stone. Zircon
is more strongly refractive than any other precious stone with the only
exception of the Diamond. It has derived its ancient name from the Arabic
zargun, which is from the Persian zar (gold) plus gun (color). Zircon is
an accessory mineral in various types of magmatic, sedimentary and
metamorphosed rocks. A remarkable property of Zircon is that its
refractive index rises when its temperature is raised.
TREATMENT: Heat treated (permanent color)
MOHS HARDNESS: 6.5-7.5 (a brittle stone, it does well in a protective
mounting)
CHEMICAL COMPOSITION: ZrSiO 4 +Fe, U, Th, Hf
REFRACTIVE INDEX: o=1.92-1.94 (often 1.925) e=1.97-2.01 (often 1.984)
(The angle light is bent traveling through a gemstone)
DENSITY (SPECIFIC GRAVITY): 4.6-4.8 (usually about 4.70)
(The number of times heavier a gemstones is compared to water)
PRINCIPAL SOURCES: Cambodia, Thailand, Sri Lanka |
