Biotite extinction
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 WebIf they’re held up to the light, they’re obvious and almost colorless, however maximum have a mild brown, yellow, inexperienced, or rose-color tint. Name: From \Muscovy …
Biotite extinction
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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. Web·Appearance, cleavage, extinction-Well developed end sections may appear as blocky four- or eight-sided crystals; more typically orthopyroxene forms stubby prisms, rectangular lathes, or ... Biotite is also pleochroic and here exists as flakes in various shades of brown (PP) and has upper 2nd order interference colors (XP).
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 … 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 appearance as it passes into extinction (Fig.1-2). Fig.1: Biotite with bird's eye extinction in a granite.
WebIt is characterized by low relief, undulatory extinction and low order interference colors. The brownish, high-relief grains (PP) are rutile ... In the XP view, the large black grain is … Web(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:
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 ... how fast is a sprintWebBiotite, XPL Biotite, Crossed Polars. Biotite displaying its characteristic birdseye extinction in cross-polarized light. A zircon with a nice decay halo is nestled into the grain at lower right … Further Reading. Biotite at … highend induction cooktop 240vWebDec 1, 2024 · Fig.7.7: Biotite in thin section: a) Sketch of biotite with one set cleavage and pleochroic haloes in PPL and XP showing straight or parall el extinction; b) … how fast is a solar sailhttp://www.u.arizona.edu/~rrhender/mineralogy%2003%20labs/03%20lab%202%20part%202.doc highend induction cooktop 240v 1inchWeb31K 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... high end indian restaurantWebextinction, has poorer cleavage, and has a pseudouniaxial interference figure. ·Brown or green tourmaline lacks biotite's It also appears darker/stronger coloredin some … how fast is a sound waveWebSometimes 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 … how fast is a stock banshee