The term that describes fragmental volcanic material is pyroclast.

Here's a breakdown:

* Pyroclast: A general term for any fragment of volcanic rock or lava ejected during an eruption.

* Pyroclastic material: Refers to the collection of these fragments, which can range in size from fine ash to massive blocks.

Here are some examples of pyroclastic materials:

* Ash: Very fine particles of volcanic glass and rock

* Lapilli: Pebble-sized fragments

* Blocks and bombs: Larger, angular, or rounded fragments

* Tephra: A general term for all sizes of pyroclastic material

Let me know if you'd like more details about specific types of pyroclastic material!