Anorthosite. Intrusive igneous, plutonic . Composed of calcic plagioclase with less than 10% ferro-magnesium minerals - plagioclase may be labradorite, bytownite, or anorthite. The name is from anorthose, an old name for triclinic feldspars. Anorthosite is often associated with gabbro
Gabbroic anorthosites occur in two localities in the canal section, in association Crude banding is seen in thin sections by the clusters of fine grained. 23 Aug 2019 Full thin section backscattered electron image. As proximity increases, modal abundance of metasomatic minerals (scapolite, amphibole, quartz) 19 Nov 1971 PETROGRAPHIC, microprobe and X-ray data were obtained from thin section 15415,14 and 1–2 mm fines 15415,28, part of the anorthositic Archean anorthosite complexes in the Superior Province are listed in Table 1. Thirty polished thin sections from all major lithological units were examined Jan 19, 2017 - Photomicrograph of a thin section showing twinned, aligned plagioclase in anorthosite. A coarse grained igneous rock, anorthosite is Anorthosite; Norite, feldspathic pyroxenites; Harzburgite, Dunite (ultramafic in thin section; It may occur as independent prisms or as crusts on the pyroxene.
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In optical mineralogy and petrography, a thin section is a laboratory preparation of a rock, mineral, soil, pottery, bones, or even metal sample for use with a polarizing petrographic microscope, electron microscope and electron microprobe. A thin sliver of rock is cut from the sample with a diamond saw and ground optically flat. It is then mounted on a glass slide and then ground smooth using progressively finer abrasive grit until the sample is only 30 μm thick. The method uses the Michel The locality contained ultramafics.
Rocks under the Microscope. Some common rock types as seen under the microscope.
HIGGINS TEXTURAL COARSENING OF ANORTHOSITE Fig. 1. Schematic diagram of the relationships of the three principal lithologies of anorthosite and troctolite. The section is ~1 m thick, but the horizontal scale is not linear. To the left the Nodular Troctolite consists of olivine oikocrysts 20–30 cm long (pale) set in a matrix of anorthosite
BRECCIA chert in silica dolomite matrix . 11 This is a thin section of Gabbro from the tertiary volcanic centre in Ardnamurchan, on the West Coast of Scotland.
Anorthite is the calcic end member of the plagioclase feldspar series. In thin section, plagioclase feldspar grains often look like they’re sprinkled with dirt (PPL) or tiny confetti (XPL). You can find the explanation on the plagioclase feldspar page. Anorthite weathers quite readily, so it’s not terribly abundant on Earth.
APALITE fine pink CO. 4. BASALT olivine, La Bajada Hill NM Quarternary. 5.
30 Oct 2007  Anorthosites, igneous rocks very rich in plagioclase,  Anorthosite, a plutonic igneous rock composed Thin section observations on. Around the Adirondack (New York) and Morin (Quebec) anorthosite masses the assemblage Minerals in thin section are pl-op-cp-bio-hb-ox- ga-qu. impermeable anorthosite layer. Thin dykes with irregular, anasta- mosing contacts extend down section from the base of the pegma- toid and may represent
open upright folds (F3) is restricted to the area adjacent to the anorthosite nappe and is interpreted as a set of visible in an outcrop or even in a thin section,. Gabbroic anorthosites occur in two localities in the canal section, in association Crude banding is seen in thin sections by the clusters of fine grained.
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Calciclasite ⓘ Labradoritite ⓘ Anorthitite ⓘ Foid-bearing-anorthosite ⓘ Troctolitic anorthosite ⓘ Charnockitic anorthosite; Foid-syenitoid. Foid-monzosyenite. Nepheline-monzosyenite … This is a thin section of one of a series of specimens very kindly sent to me from USA. Many thanks to the donor!
Dickinson et al. (1985) studied basalts from the processing fines. But Paul Warren made the most fuss, so we shall start with his observations: c1 (W-101) from ,46 and ,116
Massif anorthosite • Layring is not found in massif anorthosite.
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Grenville Province anorthosite massifs were derived from depleted mantle. It is not clear whether massifs and related mafic intrusions throughout the Nain Province of Labrador were derived from enriched mantle, or were contaminated by early Archean (greater than 3500 Ma) silicic crustal materials, heretofore thought to be restricted to coastal Labrador.
Chondrite H5 Sahara 97095. Thin Sections and polished section. Chondrite L4. Tagounite 001, Morocco 1999 sample 2.
Anorthite Crystallography. Axial Ratios: a:b:c =0.635:1:1.1003. Cell Dimensions: a = 8.177, b = 12.877, c = 14.169, Z = 8; alpha = 93.166°, beta = 115.85°, gamma = 91.216° V = 1,340.29 Den (Calc)= 2.75. Crystal System: Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P 1 ,I 1. X Ray Diffraction:
Anorthosite Thin Sections (cont.) 2.2 Secondary Minerals Quartz. Quartz can be considered as a secondary mineral in anorthosite, since it represents less than 5% on the QAPF diagram. Ths rock has a continuum of grain sizes, from very small to quite large. It does not have a phenocrystic texture, having larger crystals set in a much finer-grained matrix. The rock type is anorthosite, a cumulate rock made mostly of plagioclase. Cumulate rocks typically have the same minerals about the same size. Anorthosite: Anorthosite: A leucocratic coarse-grained plutonic rock consisting essentially of plagioclase (usually labradorite or bytownite) often with small amounts of pyroxene.
Anorthosite is often associated with gabbro rocks of the anorthosite kindred and the NE-SW direction of the quartzitic schists. The rocks are folded in small and pointed folds; the fold-axes run NS, and they are as a rule horizontal or have a slight dip towards the north. A total of 11 thin sections from mica schist Description more details.