Welded ignimbrite, Aso, Japan -- Many ignimbrites are hard, densly welded glassy rocks. The pumice fragments that characterize unwelded ignimbrites, are not easily recognizable in welded varieties because they have been compacted into black glassy pancake shapes, known as fiamme. Note the fiamme in the photo shown here. A fiamme-bearing ignimbrite is such as this is said to have a eutaxitic texture. Courtesy of Peter Francis.
For a more thorough examination of ignimbrite textures on a microscopic scale, click on microscopic ignimbrite textures.