Manning fused glass

Manning fused glass is a natural glass from east Texas, most often light blue-gray-brown. It formed when beds of lignite in the Manning Formation burned and fused the volcanic-ash-rich rock above them. It outcrops in a narrow east-west band near the Caddo homeland, north of Huntsville in Walker County. Texas Beyond History says rare black pieces can be mistaken for obsidian. The glass is scarce and breaks into small nodules and chunks, with one meter-wide nodule the largest known, so it suited small tools. It is brittle. Clovis-era use is reported, and local Caddo people also made stone tools from it. Because it is not volcanic obsidian, it is not on any obsidian source list.

A natural glass formed in the Manning Formation (a lignite-bearing unit): lignite beds burned at roughly 1,100 degrees Celsius and fused the overlying silt and silica-rich ash. The outcrop band runs north of Huntsville, Walker County.