<p>(~11.5 centimeters across at its widest)
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<hr><p>Nephrite jade (nephritite) is a greenish to blackish colored, crystalline-textured to felted-textured metamorphic rock.  It is principally composed of one or more amphibole minerals (tremolite to actinolite, Ca2Mg5Si8O22(OH)2 to Ca2(Mg,Fe)5Si8O22(OH)2).
</p><p>Some famous localities for nephrite jade in North America include Wyoming, California, British Columbia, and Alaska.  The rock seen here is Alaskan nephrite jade.  It has been eroded from glacial drift deposits in the Alaska Range and transported downstream in modern rivers.
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Locality: fluvial gravel clast, Susitna River, unrecorded/undisclosed site at or near the town of Talkeetna, south of the Alaska Range, southern Alaska, USA
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/47445767@N05">James St. John</a>
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/jsjgeology/48162872776/">Nephrite jade (fluvial clast from the Susitna River near Talkeetna, Alaska, USA) 7</a>