Biotite extinction

Author: rpdt

August undefined, 2024

WebApr 13, 2015 · Biotite has high birefringence (bright multi-colored tints) and birdseye-maple extinction in thin section. Chlorite has low birefringence (dull monochrome tints) and normal extinction. Cite Web• extinction: Bird's eye extinction, or bird's eye maple, is a specific type of extinction exhibited by minerals of the mica group under cross polarized light of the petrographic microscope. It gives the mineral a pebbly …

Muscovite Mineral Physical - Optical Properties, Occurrence, Uses

WebThe thin section captures the zone intruded by leucocratic veins during shearing. Garnet porphyroclasts are altered to biotite along their margins and in fractures. Quartz ribbons associated with leucocratic melts entrain biotite grains and display chessboard extinction (Fig. 3 B). Quartz domains include amoeboid grains that show evidence for ... WebBird's eye extinction, or bird's eye maple, is a specific type of extinction exhibited by minerals of the mica group [1] under cross polarized light of the petrographic microscope. … cycloplegics and mydriatics

Quartz NOVA Mineralogy - nvcc.edu

WebBiotite (darker in color and is pleochroic in ppl), Talc (smaller 2V), Pyrophyllite (larger 2V), birds-eye extinction and cleavage are also distinctive. Occurrence. Muscovite has a widespread occurance and is … WebExtinction: Inclined (approximately 45 degrees). Parallel when viewed down (010); Sometimes displays hourglass extinction : Dispersion: r > v : Relief: High Positive : Twinning, Lamellae: Commonly displays simple and lamellar twinning on {100} and {001}; They may combine to form a herringbone pattern. Exsolution lamellae may be present. WebSometimes the quality of the extinction can be very revealing: wavy extinction or patchy extinction often indicates that the crystal is quartz; “birds eye” extinction is a characteristic of biotite (more on later labs) or phyllosilicates in … cyclopithecus

Zircon - Clark Science Center

Web31K views 13 years ago Muscovite and biotite in cross-polarized light, showing distinctive birds-eye (mottled) extinction. Brief images in plane-polarized light show distinguish muscovite... WebExtinction: Symmetrical to cleavages: Dispersion: n/a: Distinguishing Feature: Cleavages at 56 and 124 degrees which form a distinctive diamond shape in cross section. Hornblende is easly confused with biotite. Distiguishing factors are the lack of birds eye extinction and the two distinct cleavages. Simple twinning is relatively common. cyclopinclopanhttp://sites.und.edu/dexter.perkins/opticalmin/biotite.htm cycloplegic eye refraction

"WebBird's eye extinction, or bird's eye maple, is a specific type of extinction exhibited by minerals of the mica group [1] under cross polarized light of the petrographic microscope. It gives the mineral a pebbly appearance as it passes into extinction. This is caused when the grinding tools used to create petrographic thin sections of precise ... " - Biotite extinction

Biotite extinction

WebMuscovite and Biotite micas are easily indentified in thin section because they almost always exhibit "speckled extinction" in cross polarized light (see the top two and bottom two photomicrographs below). ... through … WebBiotite shows parallel extinction in cross polarized light, and has perfect cleavage in one direction. The biotite mineral shown here is exhibits bird's eye texture during …

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http://funnel.sfsu.edu/courses/geol426/Handouts/mintable.pdf Under cross-polarized light, biotite exhibits extinction approximately parallel to cleavage lines, and can have characteristic bird's eye maple extinction, a mottled appearance caused by the distortion of the mineral's flexible lamellae during grinding of the thin section. See more Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula K(Mg,Fe)3AlSi3O10(F,OH)2. It is primarily a solid-solution series between the iron-endmember See more Members of the biotite group are found in a wide variety of igneous and metamorphic rocks. For instance, biotite occurs in the lava of Mount Vesuvius and in the Monzoni intrusive complex of the western Dolomites. Biotite in granite tends to be poorer in magnesium than … See more Like other mica minerals, biotite has a highly perfect basal cleavage, and consists of flexible sheets, or lamellae, which easily flake off. It has a See more Biotite is used extensively to constrain ages of rocks, by either potassium-argon dating or argon–argon dating. Because argon escapes readily from the biotite crystal structure at … See more

WebFeb 23, 2024 · Biotite model ages for three of the four mylonite samples cluster at c. 1750 Ma, with one sample associated with altered biotite (Fig. 4), showing a greater spread from Paleoproterozoic to ... WebOct 29, 2009 · Muscovite and biotite in cross-polarized light, showing distinctive birds-eye (mottled) extinction. Brief images in plane-polarized light show distinguish mu...

WebExtinction: Symmetrical to cleavages : Dispersion: n/a : Distinguishing Features: Cleavages at 56 and 124 degrees which form a distinctive diamond shape in cross section. Hornblende is easly confused with … WebMafic minerals are primary biotite and secondary chlorite. Plagioclase crystals are euhedral and show deformation twins as well as an ondulose extinction and have albitic composition ( Figure 4 c). Quartz crystals show undulose extinction and incipient dynamic recrystallization along their boundaries, as shown by subgrains, new grains, and ...

WebBiotite With a Halo Around a Zircon Inclusion. This sample is a biotite-cordierite-orthopyroxene gneiss from near Sioux Lookout, Ontario.The field of view, about 2 mm across, is dominated by olive-green-brown biotite.. …

http://sites.und.edu/dexter.perkins/opticalmin/quartz.htm cycloplegic mechanism of actionWebExtinction: parallel : Distinguishing Features: High relief, moderate birefringence, parallel extiction, and slender prismatic or fibrous crystal habit. Distinctive diamond-shaped cross sections with cleavage for prismatic grains. Fibrous mats … cyclophyllidean tapewormsWebBiotite is a name used for a large group of black mica minerals that are commonly found in igneous and metamorphic rocks. These include annite, phlogopite, siderophyllite, fluorophlogopite, fluorannite, eastonite, and … cycloplegic refraction slideshareWeb(vi) Extinction: angles are only given where minerals usually show a linear feature such as a cleavage and/or long crystal faces. For plagioclase feldspars (stippled) the extinction ... In igneous rocks often with biotite and K-feldspar. Also in low-med grade meta rocks. Crystals in igneous rocks often rectangular laths. Often zoned: cyclophyllum coprosmoidesWebBiotite. Mica; Sheet Silicates. Monoclinic (-) Relief - moderate. ... Extinction - straight, mottled. Comments - alters to green chlorite, often contains inclusions of accessory phases . c-axis parallel section (left) … cyclopiteWebExtinction: Undulatory: after Perkins, 303: Quartz in Hand Sample. Four variations on a theme Subhedral quartz crystal Double-terminated quartz crystals ... The quartz in this biotite gneiss is a great example. Had the … cyclop junctionsWebThe thin section captures the zone intruded by leucocratic veins during shearing. Garnet porphyroclasts are altered to biotite along their margins and in fractures. Quartz ribbons … cycloplegic mydriatics