Twinning Definition Twinning is the observed intergrowth of multiple crystals in a symmetrical fashion. This term applies to the examination of rock thin sections, in the field of optical mineralogy.

Anion Anion: In the fields of chemistry and geochemistry, an anion is a negatively charged ion. The oppositely charged ion is a cation.    

Porosity (n) “Porosity” (n), in the geological engineering field, is a percentage value that represents the bulk volume of a rock or soil, that is occupied by the void space within. Porosity (n) Formula Porosity (n) = [(Volume of Voids ÷ Total Volume) x 100%]

Settlement Definition In the field of geology, The term settlement means a gradual downward movement of the ground surface. This is generally due to soil compression at on a larger scale, atdepths that are below the ground surface.

Direct Shear Test A Direct Shear Test is a geotechnical engineering laboratory procedure that measures the shear strength value of a soil sample.