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An igneous rock consisting almost entirely of plagioclase feldspar, especially the labradorite variety.

[French anorthose, a kind of feldspar (Greek an-, not; see a-1 + Greek orthos, straight) + -ite.]

an·or′tho·sit′ic (-sĭt′ĭk) adj.


resembling or consisting of anorthosite
References in periodicals archive ?
The geologic model developed from the consistent pattern of finding PGM rich anorthositic rocks just to the east of a xenolithic contact zone between the troctolite of the SKI and the Anorthositic Series (AN-Series).
Lunar geology can be roughly broken down into two categories-the anorthositic highlands, rich in calcium and aluminum, and the basaltic "maria," giant impact basins filled with solidified lava flows that are abundant in iron and magnesium.
The drilling has intersected packages of both cumulate and intrusive style magnetite-ilmenite mineralisation intercalated with gabbroic and anorthositic country rock.
dipping magnetite rich layer about 150m thick within an anorthositic gabbro.
In addition, the overlying anorthositic, Middle Unit (MU) contains three PGE enriched zones and hole RP03-01 on the southern boundary of Rooipoort contains the best PGE values in one of these zones intersected to date (Table: 1).
The mineralization is hosted by anorthositic wallrock adjacent to the eastern margin of the SKI, and is characterized by a different tenor from most other mineralization seen thus far in the SKI.
Coughlan (1986) recognized five units in the Staples Mountain Gabbro, designated I to V from inferred bottom to top: I--gabbro, anorthositic gabbro, and olivine gabbro; II--subophitic augite gabbro; III--interlayered norite and anortbosite; IV--unlayered augite gabbro and minor olivine gabbro; V --unlayered gabbronorite, with increased orthopyroxene and no olivine, in contrast to unit IV.
The target is entirely overburden covered and four widely spaced drill holes put down in the anomaly intersected layered gabbroic to anorthositic gabbroic rocks.
The first new area of mineralization comprises PGE mineralization along the eastern side of the SKI and within the adjacent anorthositic rocks on the East Shore Property as shown in Figures 1 and 2.
The drilling has intersected stacked packages of both cumulate and intrusive style magnetiteilmenite mineralisation intercalated with gabbroic and anorthositic country rock.
2 Ma from one of the gabbroic plutons shows that the gabbroic plutons arc co-genetic with the dioritic to granitic plutons, although they show varied ultramafic to anorthositic and dioritic compositions as a result of crystal accumulation.