BH250-256

BH250-256

Spherulitic or accretionary-lapilli-bearing rhyolitic tuff

BH250-256 is a reddish-purple, fine-grained rhyolitic volcanic rock from Missouri, tentatively identified as an ignimbrite or tuff. It contains abundant rounded, millimeter-scale structures concentrated in distinct bands. These features may be accretionary lapilli formed from fine ash within an eruption cloud, or spherulites produced by the crystallization of volcanic glass during cooling. Similar features occur in Mesoproterozoic volcanic rocks of the St. Francois Mountains, including the Johnson Shut-Ins Rhyolite. This identification is provisional and will be evaluated through thin-section examination

Missouri

Bereket Haileab