Picrite


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Related to Picrite: Oceanite, ankaramite

picrite

[′pi‚krīt]
(petrology)
A medium- to fine-grained igneous rock composed chiefly of olivine, with smaller amounts of pyroxene, hornblende, and plagioclase felspar.

Picrite

 

an effusive rock composed of augite and olivine. Pi-crite also contains admixtures of hornblende, biotite, and or-thopyroxene and of various secondary minerals, including ilmenite, magnetite, and apatite. The olivine is often altered and replaced by serpentine, as well as by iddingsite, chlorite, and sometimes actinolite.

Picrites are holocrystalline. However, they sometimes contain a certain amount of glass inset with augite and olivine (picrite porphyry). The chemical composition of picrites is 38–41 percent SiO2, 5-10 percent Al2O3, and 20-29 percent MgO.

References in periodicals archive ?
However, the present exposures of picrites in the Deccan province are limited and their PGE contributions seem quite insufficient to approach the magnitude of the K-T Ir anolmaly (Sutherland, 1994).
Extraction is continuing on unmineralized gabbroic dolerite and picrite.
Tenders are invited for Tender For Bags Calico For M T Propellant And Picrite Bag Made Out Of Calico Cloth As Per C.
Loading, Unloading & Shifting Of Picrite Filled Cardboard Boxes Of Net Wt.
The petrogenesis of Gorgona komatiites, picrites and basalts: new field, petrographic and geochemical constraints.
Their geochemical features, the presence of interpillow Paleocene pelagic limestones, and that of picrites are features quite similar to those of the Turrubares Unit.
These rocks contain more than 18 wt% MgO (Le Bas 2000) and are distinguished from other magnesium-rich rocks, such as picrites and meimechites, by having spinifex texture (characterized by spectacular arrays of subparallel or randomly-oriented skeletal, platy and bladed olivine crystals set in a glassy groundmass; Fig.
For example, with respect to the MgO contents of common ultramafic magmas, komatiites characteristic of the Archean have >18 wt% MgO, komatiitic basalts dominant in the Proterozoic have 12-18 wt% MgO and picrites in the Phanerozoic have 10-13% wt% MgO.