The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. The cookie is used to store the user consent for the cookies in the category "Performance". Ultramafic soils are characterized by severe edaphic conditions induced by a low content of essential nutrients, an adverse. This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other. The cookies is used to store the user consent for the cookies in the category "Necessary". The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". The cookie is used to store the user consent for the cookies in the category "Analytics". This cookie is set by GDPR Cookie Consent plugin. IUGS MAFIC PLUTONIC Rocks Ternary Plots Mafic Plutonic Rocks P P plagioclase feldspar anorthosite Px pyroxene 90 Ol olivine 80 LEUCO-GABBROIDS > 65 plagioclase 70 gabbro or 60 troctolite norite 50. These cookies ensure basic functionalities and security features of the website, anonymously. Necessary cookies are absolutely essential for the website to function properly. Similarly, Ca-rich compositions lie towards the right of the diagram, since clinopyroxene is the only mineral in the diagram that contains Ca. This is because pyroxenes stoichiometrically contain more silica than olivine. SiO 2-poor compositions lie close to the top vertex (dunite), whereas SiO 2-rich compositions occur at the base of the diagram. This diagram defines very well the first-order chemical variability of ultramafic rocks. ‘Olivine’ is specified in the name in pyroxenite varieties with an olivine content between 5 and 40% (e.g. Websterite: consisting of clinopyroxene and orthopyroxene.Ĭlinopyroxenite: with clinopyroxene > 90%. Orthopyroxenite: with orthopyroxene > 90%. Wehrlite: consisting largely of olivine and clinopyroxene. Lherzolite: a peridotite with olivine, orthopyroxene, and clinopyroxene. Harzburgite: consisting predominantly of olivine and orthopyroxene. Two broad fields are separated based on the modal content of olivine: peridotites (olivine > 40%) and pyroxenites (olivine 90%). For ultramafic rocks containing hornblende (extremely rare) the diagram below should be used instead. SiO 2 diagram shown below) Note that at each stage of the process, the classification may change, but it is important to keep in mind that each stage has. Most ultramafic rocks consist of the three minerals in this diagram: olivine, ferromagnesian pyroxene (orthopyroxene, enstatite), and calcium pyroxene (clinopyroxene, diopside). Chemical analyses can be obtained, and a chemical classification, such as the LeBas et al., IUGS chemical classification of volcanic rocks (based on total alkalies Na 2 O + K 2 O vs. IUGS classification of ultramafic rocks with olivine, orthopyroxene, and clinopyroxene.