The Three Faces of Jade
Lecture Review by Eric J. Hoffman
Tripartite Banquet Lecture 11 September 2013 by the New York Mineralogical Club.
The New York Mineralogical Club, with more than 250 members, dates back to 1886. It holds monthly meetings with guest lecturers, conducts field trips, and publishes a bulletin with news, announcements, and original articles about minerals and gemstones. The Club’s annual banquet, held September 11th in midtown Manhattan, featured a tripartite lecture on the fascinating but often confusing gemstone, jade.
The evening began with a silent auction featuring minerals, gems, books, and of course some jade. Following a delicious dinner president Mitch Portnoy introduced the evening’s topic with an entertaining slide show of jade art treasures, set to Puccini’s Turandot. Vivien Gornitz was the lead-off speaker, comparing the mineralogy and geology of the two types of true jade, nephrite and jadeite. She discussed the differences between Burmese and Guatemalan jadeite and also clarified some of jade’s confusing cousins, such as omphacite and Maw-sit-sit. Jade’s many imitators were explored as well. Portnoy then presented an overview of the art and archeology of jade usage in cultures throughout the world. Every culture that had access to jade valued it highly and fabricated it into designs that show remarkable similarity.
There was plenty of information for even the most jade-savvy attendees. Jade’s colorants, for example, were explained in detail. Iron is the principal green colorant for both types of jade; for jadeite chromium provides the brilliant “Imperial” green and manganese a delicate lavender. The geology of jade is also fascinating. It is called the “plate tectonic gemstone” because it forms from the subduction process as one plate slides beneath another. This accounts for the prevalence of jade findings around the Pacific “Ring of Fire.”
The final speaker, Anna Schumate, explored the world of jade jewelry, illustrating jade’s gemological properties with interesting case studies. Of course this principally involved jadeite, with its wider range of attractive colors, but nephrite’s use in jewelry was discussed as well. She illustrated the risks of dyed or polymer enhanced jadeite with example photographs.
A fascinating evening devoted to my favorite stone! And every attendee walked away with a handful of gifts, including a jade color chart, a Wyoming nephrite cabochon, and a bookmark with jadeite tassel.
Copyright © 2013 by Eric J. Hoffman (Home Page)
Originally published in ASJRA Newsletter, November 2013