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Friday, April 13, 2012

Jade and Gold


A piece of uncut jade
photo by Immanuel Giel


According to John Sinkankas (1959) there is one small deposit of jade found in an undisclosed location in California that exhibits small flecks of gold making it a rarity.  Too say the least your author has seen one polished example of this jade, and it is quite handsome being green with specks of gold throughout. 

California contains both jadeite and nephrite two distinct minerals with jadeite being a pyroxene mineral while nephrite is an amphibole intermediate between actinolite and tremolite.  They are both found in a high pressure/low temperature environment like that found in the coastal ranges of California

This geological environment is considered by many geologists to be blue schist facies.  One area near Monterrey called Jade Cove is a place where many large boulders of jade have been found in the Pacific Ocean.  These boulders are usually found covered with a tannish crust caused by weathering.  The true nature of these boulders is not seen until this crust is broken through.

A nephrite desk set by Faberage
Photo by Shakko


Jadeite is a member of the pyroxene group of minerals with a composition of sodium aluminum silicate (NaAlSi2O6).  This variety of jade is found in California and other places in the world.  The most precious form of jade called Imperial Jade by the Chinese comes from Burma.  Jadeite deposits are relatively rare.

Nephrite jade sometimes called Wyoming Jade the state gemstone was first found in the Granite Mountains in central Wyoming with the most intensive exploration taking place from 1940 through 1960, but recent activity in the jade producing areas indicate a new interest in this gem.  Most of the high-grade nephrite jade has been found in alluvial deposits in and around the Granite Mountains in central Wyoming.

A Mayan facemask made from jadeite


Other large scale deposits of this mineral are also found in Alaska and British Colombia the finest jade in the world however is that found in Wyoming.

Nephrite is calcium magnesium silicate [Ca2(Fe, Mg) 5Si8O22(OH)2. some of the nephrite found in Wyoming is colored emerald green by chromium atoms entrapped in its crystalline structure,  The normal green is caused by iron atoms and black nephrite is caused by an excess of iron.  When iron is absent the color is colorless, but appears cloudy white because of its fibrous structure.

Nephrite containing specks of gold is rare so far only known from one locality in California.  Further investigation will eventually locate further localities.

5 comments:

  1. I have a piece of dark green.Jade with. Hundreds of gold specals what is it worth I made it into a stone for a ring

    ReplyDelete
  2. I have a piece of dark green.Jade with. Hundreds of gold specals what is it worth I made it into a stone for a ring

    ReplyDelete
  3. I have a piece of dark green.Jade with. Hundreds of gold specals what is it worth I made it into a stone for a ring

    ReplyDelete
  4. I have a piece of dark green.Jade with. Hundreds of gold specals what is it worth I made it into a stone for a ring

    ReplyDelete