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...
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:
And, just because, here's a photo from http://www.geus.dk/cgi-bin/webbasen_nyt_uk.pl?pagenum=12%7Ccgifunction=Vis
of a "Eclogitic mantle xenolith from a kimberlite dyke in the Maniitsoq area, southern West Greenland. Photo: J.Lautrup, GEUS." - whatever that means.