Pronunciation: TUFF (as in "tough")
Description*: Tuff is a volcanic or volcaniclastic rock formed of material that accumulated on or around the volcano after an eruption. Tuff has a pyroclastic texture. Ash-fall tuff is a fine-grained rock composed of volcanic ash. Oth
er examples of tuff may have the look of a coarse breccia (or concrete with angular aggregate), with broken angular pieces of whatever was blasted out of the volcano or carried along in a pyroclastic flow.
Sometimes, older tuff layers can be metamorpho
sed by the heat and weight of subsequent tuff deposition into a dense silica-rich rock called a welded tuff.
*Description from Cronin, V.S., 2001, Geology laboratory projects for group learning: Primis McGraw-Hill, 156 pp., ISBN 0-07-252348-4
Used by permission of the author.
Return to the Minerals, Igneous Rocks, Metamorphic Rocks, or Sedimentary
Rocks page.
Return to Geo 100 Page
This web document was created in 2002 by Vince Cronin
