Why is it called Omphacite Jadeite?

January 9, 2019

 

 

Known as Mo Cui or Mexican Green in China and Inky Jade in Hong Kong, this extremely rare and coveted gemstone has gone by many names. The name that is most often seen in the English language calls this stone Black Jadeite but is it really jadeite? Why is it often referred to as Omphacite Jade? This article will attempt to point out an answer to these questions that have been recently discussed in a GIA article entitled The Jadeite/Omphacite Nomenclature Question.

 

 

Imperial Translucent Black Omphacite Jadeite Jade

 

 

 

To first begin to understand this difficult question of what to name a mineral we must first look at the official scientific groupings of minerals as the GIA’s Carlsbad laboratory did in 2012. In early 2012, The GIA Laboratory in Carlsbad, California received a sample for testing that looked and tested as jadeite yet turned out to be mostly omphacite as was evident only by its slight difference in Raman spectra.

 

 

According to the GIA, “Members of the series, while all related to one another, are actually different minerals based on changes in chemistry and/or structure. In this case, jadeite’s chemical formula is NaAlSi2O6, while omphacite’s is (Ca,Na)(Mg,Fe2+,Al)Si2O6. What this means is that sometimes the borders between members can become indistinct—not from a mineralogical point of view, but from a practical perspective.”

 

 

 

Imperial Translucent Black Omphacite Jadeite Jade

 

 

 

 

As further investigation found “This result caused us to wonder how many stones that look like jadeite and test as jadeite are actually omphacite. We started collecting Raman spectra on every piece of jade that came through the lab and found that while most pieces were indeed jadeite, a surprising number were omphacite. The more we looked, the more interesting our observations became. Pieces whose gemological properties were absolutely identical to jadeite—appearance, color, texture, RI, SG, and absorption spectra—were identified as omphacite by their Raman spectra. Even some fine-quality pieces with the appearance and characteristics of Burmese jadeite fell into this category.” Omphacite Jade which has also been endorsed by the Chinese/Hong Kong mineralogists who have accepted it as Fei Cui, a term used to describe finely textured jadeite.

 

 

 

Imperial Translucent Black Omphacite Jadeite Jade

 

 

 

 

To the naked eye, omphacite jadeite and jadeite can be identical in appearance as the two are so similar that only laboratory tests can confirm the true identity through the use of Raman spectra analysis. 

 

Imperial Translucent Black Omphacite Jadeite Jade

 

 

 

HeavensStoneZ chooses to embrace this scientific nomenclature of Omphacite but also feels it necessary to add the word jadeite, as all of the samples tested contained both minerals in different ratios. HeavenStoneZ feels it appropriate to use the trade name of Imperial Translucent Black Omphacite Jadeite Jade in accordance with present international classifications of this mineral.

 

 

For referenced GIA article:

https://www.gia.edu/ongoing-research/the-jadeite-omphacite-nomenclature-question

 

 

 

 

 

 

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