Really need help identifying this rock (not much of a rock expert)!
A Little more info: Found lying amongst quite a bit of basalt and some common metamorphic rocks (gneiss etc...)
Please help!
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Really need help identifying this rock (not much of a rock expert)!
A Little more info: Found lying amongst quite a bit of basalt and some common metamorphic rocks (gneiss etc...)
Please help!
++2011-11-28_21-46-50_486.jpg
not enough detail to give it a name beyond possible extrusive igneous rock
Some thoughts:
I'm not sure why Paleoichenum is suggesting an extrusive igneous rock. The crystal size is quite large, so cooling was reasonably slow.
The texture appears more like a metamorphic one than an igneous one. There is definite orientation of mineral (though that is not uncommon in lava flows).
The light mineral is probably a feldspar. There is a greenish tinge also which suggests an olivine or pyroxene.
If this is igneous the large crystals are most certainly not in equilibrium with the melt. They are almost certainly ferro-magnesians silicates of some sort.
I don't see any quartz.
Do you have any other views of it? Especially one where the large crystals are not in shadow?
I siad external extrusive due to the context where it was found and the large structures on the right face appearing to either be chipped surfaces or lichen/staining. The left face and top face both show a very fine mix of minerals with little in the way of distinct crystals.
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