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Psephite (Greek: psephos, pebble) is either a sediment or sedimentary rock composed of fragments that are coarser than sand and which are enclosed in a matrix that varies in kind and amount. It is equivalent to a rudite. Shingle, gravel, breccia, and especially conglomerate, would all be considered psephites. It is equivalent to the Latin-derived term rudite. Psephite is more commonly used for a metamorphosed rudite.[1]

Pettijohn [2] gives the following descriptive terms based on grain size, avoiding the use of terms such as "clay" or "argillaceous" which carry an implication of chemical composition:

Descriptive size terms
Texture Common Greek Latin
Coarse gravel(ly) psephite (psephitic) rudite (rudaceous)
Medium sand(y) psammite (psammitic) arenite (arenaceous)
Fine clay(ey) pelite (pelitic) lutite (lutaceous)


  1. ^ Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, J.A., eds. (2005) Glossary of Geology (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. ISBN 0-922152-76-4
  2. ^ Pettijohn F. J. (1975), Sedimentary Rocks, Harper & Row, ISBN 0-06-045191-2