Fiamme

Fiamme are lens-shapes, usually millimetres to centimetres in size, seen on surfaces of some volcaniclastic rocks.

Fiamme are most typical of welded lapilli-tuffs and are commonly found in association with eutaxitic textures, best seen under the microscope.

Some fiamme represent fragments of volcanic ejecta, often pumice lapilli that have been flattened by compaction and/or shear.

Some fiamme are formed from flattened hot, relatively low viscosity, high porosity fragments of volcanic glass or pumice.

Fiamme can also result from patchy alteration and recrystalisation of volcanic rocks, or by patchy revesiculation of welded tuff matrix (especially in rheomorphic peralkaline tuffs).