pyroclastic tuff balls - hand specimens of unusual tuff snowballs

Here is something different. These pyroclastic tuff balls were found weathering out of a pumice bed. We have looked at a lot of pumice over the years, and have never seen anything like these. They must have formed in a pyroclastic flow somewhat like snowballs. The primary materials of the flow are pumice, tuff fragments and volcanic ash. As this mixture was blasted downhill, rolling and slightly melted fragments of tuff acted like snowball cores, picking up still glowing hot ash and other tuff fragments. This particular flow is exposed in only a small area, so we are surprised when a few more weather out.  These tuff balls range in size from roughly a golf ball to a baseball in size. They are being offered in sets with different sized examples in each set. Some are fairly lumpy with included fragments of tuff.      Select a set: When more than one set is shown, you can select a particular set by telling us what is in the photo with it, a black and silver pen, a black mechanical pencil,