Saturday, October 16, 2010


During the recent rescue of the miners in Chile, Denise heard a TV commentator discussing various types of rock and the drilling procedures required to punch through them. The word clastic caught Denise’s attention, and she asked for some information.

Clastic rocks are fragments of pre-existing rocks. They may range in size from a grain to a boulder. The parent rock may be broken apart over time by erosion or weathering or crushing. The word comes from the Greek κλαστοσ (klastos), meaning broken. To serve as a specific example, pyroclastic rock is rock fragmented by volcanic action.

The word clastic also applies to anything that may be taken apart, like an anatomical model. For example, the model of an eye might be found in an optometrist’s examination room or a model of the brain may be found in a physician’s office. If it breaks into parts for instructional purposes, it is clastic.

The word part –clast is often used in the sense of destruction. A biblioclast destroys books, especially the Bible. Dendroclastic refers to the breaking or destruction of trees. An iconoclast destroys sacred images; the word idoloclast is also used. A mythoclast debunks myths.

When she broke my heart, she became a cardioclast.

Available from McFarland & Co.: Word Parts Dictionary, 2nd edition

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