Why this rock is probably not a meteorite:
This is a sawn face of a large rock. The round things could be chondrules in a chondritic meteorite, but they're probably not. First, the specific
gravity of the rock, 2.8, is too low for a chondrite. Second,
chondrules are not usually this big. Third, chondrules don't have
rims like this. Fourth, there's no metal, so it's not an ordinary
chondrite; it would have to be a type of rare chondrite. Finally,
the matrix is too fine-grained for any type of chondrite (see Allende
photos here).
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What is it?
This sample is a piece of a pickup-truck-sized rock found in northeast
Missouri. We were so fascinated by the texture that we had a petrographic
thin section prepared. We think this was a basalt with olivine phenocrysts
that has been hydrothermally altered (very hot water). It's probably
from the northern Midwest or Ontario and was transported to Missouri
by glaciers.
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