Psephite (Greek: psephos, "pebble")[1] 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.[2]

Pettijohn [3] 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
TextureCommonGreekLatin
Coarse gravel(ly)psephite (psephitic)rudite (rudaceous)
Medium sand(y)psammite (psammitic)arenite (arenaceous)
Fine clay(ey)pelite (pelitic)lutite (lutaceous)

References

  1. ψῆφος. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project.
  2. 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
  3. Pettijohn F. J. (1975), Sedimentary Rocks, Harper & Row, ISBN 0-06-045191-2


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