Tuesday, October 26, 2010

xenolith/xenocryst



My new word for the day is XENOLITH.
Yesterday I would have called this "a chunk of some sort of crystal of something in this other stone" ( like I did here: Leominster Familiar Shape), but today I can proudly say that, after a few hours of reading about the geology of Connecticut and getting very confused about terms, I learned this new word at Rock Piles (Bears Rocks, Pennsylvania) via a comment by Doug Watts (who actually knows one rock from the other by name, unlike me, and to whom I considered sending every picture of every rock I've ever taken - for a second or two until I thought about it for a second or two more) .
I just happened to notice the thing for the first time just yesterday because the light rain really makes the colors and details of these stones show up really well...
 
XENOLITH: a fragment of a rock included in another rock

First Known Use of XENOLITH: 1894 - Rhymes with XENOLITH (I already knew that!)

"A xenocryst is an individual foreign crystal included within an igneous body (http://en.wikipedia.org/wiki/Xenolith)."

My intention was to photograph these little turtles, split out of stones so the crystal looks like a turtle head sticking out of a shell...

(The turtle with the X-head stone is at about 5:00 from the center of the above photo),
sitting in what looks like the rest of the stone it was broken out of.) 

Here's another, downhill from the other but still on the same mound:  
The two Little (Xenolith) Turtles the first one pictured circled in yellow, the second circled in red, and the much larger Turtly-looking Stone.
Here's a third one above & a fourth below:


of a "Eclogitic mantle xenolith from a kimberlite dyke in the Maniitsoq area, southern West Greenland. Photo: J.Lautrup, GEUS." - whatever that means.



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