Plinthite: Litho-plinthite (laterite) from Brazil

Plinthite is a material that is made up of iron oxides and forms deep in soils under certain specific conditions. Petroplinthite forms from the hardening of continuous phase plinthite. In many parts of the world, petroplinthite is mined, cut into shape, and used as building blocks. It has not been recognized in the US.

 

In progression are:

Plinthite--non-cemented to moderately cemented

Petroplinthite--nodular and strongly cemented or very strongly cemented

Litho-plinthite--vesicular (tubular) strongly cemented or very strongly cemented (obsolete)

Ironstone--indurated

 

The soil layer illustrated in this photo was cemented (had hardened upon exposure), but the degree of cementation was less than strongly cemented.

 

For more information about describing and sampling soils, visit:

www.nrcs.usda.gov/resources/guides-and-instructions/field...

or Chapter 3 of the Soil Survey manual:

www.nrcs.usda.gov/sites/default/files/2022-09/The-Soil-Su...

 

For additional information on "How to Use the Field Book for Describing and Sampling Soils" (video reference), visit:

www.youtube.com/watch?v=e_hQaXV7MpM

 

For additional information about soil classification using USDA-NRCS Soil Taxonomy, visit:

www.nrcs.usda.gov/resources/guides-and-instructions/keys-...

or;

www.nrcs.usda.gov/resources/guides-and-instructions/soil-...

 

Done