This photo is of a long tube pumice lapilli shard from the Wildcat Creek beds, Ohanapecosh Formation. The Ohanapecosh Formation contains early eruptions from the ancient Cascades in Washington State.
Pumice is a highly vesicular rock. The long tube varieties exhibit parallel gas escape structures running longitudinally within the rock, which can be seen in thin section (see below). The blue-green color is from the clay mineral product, clinoptolite, of the alteration of the original volcanic glass.
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