What is it?
Someone found this rock in a mineral collection that he purchased
from a geologist and sent it to us to examine. It didn't have a label.
This rock is almost certainly a fulgurite - a rock
form by lightning striking the ground. It's cylindrical, with a glassy
center and exterior composed of fused rock and soil. The top photo
shows a side view; the two bottom photos show the broken ends, looking
down the cylindrical axis. Glassy areas (dark green) occur in all
views.
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