This specimen of fulgurite (a variety lechatelierite) is from the Bouarfa area of Morocco. It forms a half tube.
Thumbnail Specimen: About 2.0" long x 0.7" diameter (50mm x 18mm).
Fulgurites (from the Latin fulgur, meaning "lightning") are natural tubes, clumps, or masses of sintered, vitrified, and/or fused soil, sand, rock, organic debris and other sediments that sometimes form when lightning discharges into ground. Fulgurites are classified as a variety of the mineraloid lechatelierite.