Nephrite is categorized as an amphibole and consists of extremely dense and compact fibrous tremolite-actinolite; and jadeite is categorized as a pyroxene, and also forms dense and compact material.
|Light green muttonfat jade from the Granite Mountains. Note the crystal is |
hexagonal (6-sided) just like quartz. This jade replaced a former
quartz crystal leaving behind this rare pseudomorph) (W. Dan Hausel,
|Look closely at this jade and you will see several individal jade crystals that are roughly hexagonal. These are also jade|
pseudomorphs after quartz. During the geological past, the jade slowly replaced the quartz one atom at a time without
disturbing the original crystal habit of the quartz (W. Dan Hausel, collection).
Jade ranges from opaque to translucent masses and has a vitreous to waxy luster and is reported in a variety of colors including black, white, and several shades of green. The green color is due to the presence of iron. When iron is absent, the mineral is practically colorless to cloudy white, resulting in a variety known as ‘muttonfat jade’. Other varieties of jade include translucent, emerald-green ‘imperial jade’; ‘apple-green’ jade, ‘olive-green’ jade, ‘leaf-green‘ jade, ‘black‘ jade, and ‘snowflake’ (mottled) jade. The greater commercial values are attached to the lighter green translucent varieties. Rare emerald green jade is colored by iron and trace amounts of chromium.
When found in outcrop, nephrite jade is associated with this distinct assemblage of minerals that form an alteration halo around jade. This halo consists of bleached leucocratic (white) granite-gneiss that is mottled pink and white, some secondary greenish clinozoisite, pink zoisite, pistachio green epidote, green chlorite and fine white mica. This alteration halo can be used as a guide to find hidden jade deposits. While exploring between some jade deposits north of Jeffrey City to the jasper deposits in the Tin Cup district to the west, I found more than a dozen such halos – a couple had exposed jade, others did not. The ones without jade, such as shown in the photo below, likely have hidden jade at shallow depth.
|Black Jade from Wyoming|
|Another strange rock. A former igneous rock (trachyte porphyry) from|
the Granite Mountains, Wyoming, that was replaced by nephrite jade (W.
Dan Hausel collection).
|Geisha dressed in jade - |
colored pencil sketch.
|Massive emerald green Wyoming jade|
|Extraordinary specimen of polished|
jade from Wyoming with rind
ABOUT THE AUTHOR -
GemHunter, was privileged to work as a research geologist for the Wyoming Geological Survey at the University of Wyoming for three decades. During those years, he periodically took leave of absence to consult on gold, diamond, and gemstones in the search for additional deposits outside of Wyoming. Over the years, he published more than a thousand books, maps, professional papers and abstracts, and mapped more than 1,000 square kilometers of complex geological terrain, while finding hundreds of mineral anomalies including one of the largest gold deposits ever found on earth (with 6 colleagues).
|My good friend, Dr. J. Dave Love (RIP) sits on large Wyoming jade boulders in a garage in Wyoming.|