1. The condition of a clay body in the kiln when heated to vitrification. At this point, any impact upon the pot may alter its shape, and, ultimately, it may begin to sag under its own weight.
2. Pyroplastic rocks are those that have been formed by fire: "The rock and dirt that made the top of the mountain was pulverized in the explosions, and was carried down the mountainside in a series of blasts of hot air called pyroplastic flows."
3. Rocks that have been formed by high viscosity lavae with a high percentage of glass, or by pyroplastic materials (ignimbrites) are derived from explosive activities.

Examples in which the term pyroplastic is used:

1. In AD 79, Vesuvius did it's worst with lots of pumice (which didn't really pose that much of a danger in this case, because it was so light) and a number of pyroplastic flows (extremely hot choking burning winds with lots of ash, hot unbreathable gas and debris) finally finished the place off and the Romans never reinhabited the site.
2. A town completely preserved underneath the ash of a volcanic pyroplastic explosion.
3. Pyroclastic flows are a majestic sight. It's easy to be led into a false sense of security by their beauty.
4. With reference to Mt. Saint Helens (May 18, 1980): The eruption cloud eclipsed the sun in Yakima which is roughly 150 miles away from the mountain itself, and the ash choked cities thousands of miles away as the volcanic plume traveled all the way around the globe, taking the pollution it carried with it.
5. The eruption also created a lehar (a volcanic mudslide consisting of mud, rock and water that is much like wet concrete) that traveled 100 miles from the blast zone and also destroyed almost everything in its path.
6. Some even argue that lehars are the most lethal part of a volcanic eruption, although others argue that it is actually the pyroplastic flow.