File:Dunham classification EN.svg

English: Classification of carbonate rocks into six types by Dunham (1962; top row). The first four of these types are for rocks made of clasts that were deposited by sedimentary processes (so they were originally not from the place where the rock formed). If a carbonate rock with a matrix of mud is clastic it can be a "mudstone", "wackestone" or "packstone" depending on the volume% of the clasts. A mudstone has less than 10% clasts. A wackestone has more clasts, but not enough to be clast supported: then it would be a packstone. When the matrix is made of crystalline cement instead of mud, the rock is a "grainstone". If a rock is made of a biogene framework, not transported and deposited but still at the same place where the rock formed, it is called a "boundstone". Finally, some carbonate rocks are entirely crystalline: no depositional features are visible (last of the six boxes in the top row).

The lower row shows the additions to Dunham's scheme by Ebry & Klovan (1971), who added five more types. Wackestones and packstones with more than 10% of the clasts larger than 2 mm were called "floatstone" and "rudstone", respectively. Also, boundstones were subdivided into three types: "framestone" (in which the entire rock is made of a biogene framework), "bindstone" (in which the rock has been formed by organisms that encrust and bind, like stromatolites and algae), and "bafflestone" (in which mud accumulated inside and around in-situ organisms that baffled it).

• Dunham, R.J. 1962: Classification of carbonate rocks according to depositional texture. In: Classification of Carbonate Rocks (Ed. W.E. Ham), American Association of Petroleum Geologists Memoirs 1, 108–121.
• Embry, A.F. & Klovan, J.E. 1971: A late Devonian reef tract on northeastern Banks Island, N.W.T. Bulletin of Canadian Petroleum Geology 19(4): 730–781.
• Lokier, S.W. & Al Junaibi, M. 2016: The petrographic description of carbonate facies: are we all speaking the same language? Sedimentology 63(7): 1843–1885.