[Rockhounds] olivine

[larryrush at att.net]

Those members who expressed an interest in Kitty's post about peridot may be
interested in olivine nodules in basalt that come from the San Carlos Indian
reservation, in Gila county, Arizona (and a few other sites). The
phenocrysts there are composed of masses of olivine granules, which weather
out of the rock like so much green sand. The mineral does not occur as loose
crystals, except perhaps as micros. Kitty's "green sand" beach is probably
derived from a like occurrence.

The specimens in Ariz. are mined by the Indian members on the reservation,
and are marketed to collectors. The locality is prolific, but can be
accessed only by a local Indian miner or by using them as a fee guide to the
diggings.

The petrology of these relatively rare occurrences can be found in a good
rock or mineral book.  For a photo of one of these larger pieces, see..     

 

https://tinyurl.com/y8p8ajb6  

 

(hope this works-I have trouble with photo-sharing these days since Picasa
is gone- suggestions welcomed!)

 

Larry Rush

 

 

 



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