changing colors of plagioclase feldspar

Revision 1 Study on structure variations of ...

47 Introduction 48 Plagioclase feldspar (CaxNa1-xSi3-xAl1+xO8), a coupled solid solution between albite (NaAlSi3O8) 49 and anorthite (CaAl2Si2O8), is the most abundant group of minerals in the Earth''s crust.The 50 intermediate labradorite feldspars (An50~An70) are common in mafic rocks.Plagioclase with 51 composition between ~An25 to ~An75 often show satellite diffractions (e-reflections ...

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Plagioclase

Petrologists distinguish the position of a plagioclase along this series using two numbers- %Ab (percent albite) and %An (percent anorthite.) Plagioclases are triclinic and have a Moh''s hardness of 6 to 6 ½. The pure sodium feldspar, albite has the formula NaAlSi3O8 and the pure calcium endmember, anorthite has the formula CaAl2Si2O2.

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Olivine, Cordierite and Feldspar

Plagioclase feldspars. commonly twinned, twin planes produce parallel striations on mineral''s surface; gem varieties: Labradorite: - dark grey color, irridescent - play of color is referred to as ''labradorescence''. some wavelengths are amplified, and some are …

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Feldspar

The most important gem member of the plagioclase group is labradorite, the chief attraction of which is its change of color that may be visible at one angle across the entire surface of the stone. This effect is created by light interference set up by thin plates of feldspar that result from repeated twinning.

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Plagioclase Feldspar: A group of common rock-forming minerals

What is Plagioclase? "Plagioclase" is the name of a group of feldspar minerals that form a solid solution series ranging from pure albite, Na(AlSi 3 O 8), to pure anorthite, Ca(Al 2 Si 2 O 8).Minerals in this series are a homogenous mixture of albite and anorthite. The names of the minerals in the series are arbitrarily given based upon their relative abundance of albite and anorthite.

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Feldspars

 · Feldspars - all about the plagioclases and K-feldspars. Feldspars are alumosilicates of alcalic metals and form a significant portion of many volcanic and metamorphic rocks. As such, they are one of the most important mineral groups on the Earths surface: some estimate that they form between 50-60 % of the Earths crust.

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Labradorite: Meaning, Healing Properties and Powers

A semi-precious plagioclase stone with a Feldspar substance that usually reveals a variety of colors if light touches it is called Labradorite and the flashing of colors is called "labradorescence" or "adularescence". Spectrolite is also another name for this dazzling stone.

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color change feldspar

color change feldspar. Feldspar Distinctions, Characteristics Identification. 10/08/2019 Alkali feldspar (also called potassium feldspar or K-feldspar) has a color range from white to brick-red, and it''s typically opaque. Many rocks have both feldspars, like granite. ... Rock formed almost entirely of calcic plagioclase feldspar is known as ...

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Labradorite feldspar

Labradorite properties. A feldspar mineral, is an intermediate to calcic member of the plagioclase series. It has an anorthite percentage of between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573. And the twinning is common.

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Feldspars – Strike-dip

Feldspars. Feldspars are one of the most common minerals on Earth. There are two solid solution series of feldspar minerals: alkali feldspars and plagioclase feldspars. The end members of these solid solutions are potassium feldspar (orthoclase, microcline) (KAlSi 3 O 8) – albite (NaAlSi 3 O 8) – anorthite (CaAl 2 Si 2 O 8 ).

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Plagioclase: Mineral information, data and localities.

Dickson, F.W. (1968) Growth of K-feldspars and plagioclase by replacement processes in rock of the Papoose Flat pluton and in country rocks, Inyo Mountains, California. Geological Society of America Special Papers 101, Abstract for 1966: 53-54.

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Feldspar

Feldspar - Feldspar - Identification of specific feldspars: Alkali feldspars can often be distinguished from plagioclase feldspars because most grains of the latter exhibit albite twinning (see above Crystal structure), which is manifested by parallel lines on certain cleavage surfaces, whereas grains of alkali feldspars do not. This criterion is not, however, absolute; some plagioclase ...

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A spectroscopic study of blue radiation coloring in ...

Blue color in sodic plagioclase is produced by electronic transitions of Pb in a manner similar to the mechanism causing color in amazonite (potassium feldspar colored blue-green by Pb electronic transitions). The two blue feldspar varieties have the following

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Plagioclase

Plagioclase and Augite in a Basalt. The photos above show abundant plagioclase lathes (clear - PP; low order interference colors - XP) and the clinopyroxene augite (almost clear- PP; 2nd order yellow to blue to pink interference colors-XP) in a matrix that contains a lot of brown glass.Two vesicles are also present (clear, PP; isotropic, XP) -- one left of center on the bottom edge, and the ...

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Plagioclase Group Solid solution between Albite Anorthite ...

The plagioclase feldspars can range in color from colorless to white to greenish yellow and even flesh red. They have a vitreous, pearly luster. Polysynthetic twinning is diagnostic of plagioclase. See hand sample 1844 as a good example of what to look for. The plagioclase feldspars show perfect {001} cleavage and good {010} cleavage.

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Feldspar

Feldspar color is due partly to tiny mineral inclusions in the pores, hematite in pink and red feldspars and Fe–Ti oxides in gray and white feldspars. ... Plagioclase feldspar (Na,Ca)(Al,Si) 4 O 8 is a solid solution between albite ... but a rough estimate of 0.3% was obtained for the excess-water experiment using the net change in absorbance ...

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Melting kinetics of a plagioclase feldspar | SpringerLink

Partial melting experiments on plagioclase feldspar have been carried out to investigate textures and kinetics of the melting. A labradorite single crystal was heated at one atmosphere pressure and temperatures within its melting interval as a function of time. So called honeycomb, fingerprint, or sieve textures were produced except for the runs just below the liquidus.

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Feldspar

Plagioclase Orthoclase: Feldspar is a name given to a class of aluminum-containing silicates which are sometimes called light silicates or "nonferromagnesian silicates" since they don''t contain iron or magnesium. The feldspars include orthoclase (KAlSi 3 O 8) and plagioclase ((Ca,Na)AlSi 3 O 8).Note that the plagioclase differs from the orthoclase in terms of the additional metals, plagioclase ...

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Feldspar

The plagioclase feldspars represent the "continuous branch" of Bowen''s Reaction Series, and form a complete series between anorthite (the pure calcium member), and albite (the sodium-rich variety). I once saw an estimate that said that 60% of the earth''s crust is composed of feldspar.

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Plagioclase feldspar | Bryn Mawr Mineralogy Wiki | Fandom

Thin Section: low relief, lack of color, biaxial character, and polysynthetic twinning distinguish pla. from most other silicates. Relations to Other Minerals Similar minerals: K-feldspar lacks of parallel striations and is more commonly pinkish in the common igneous rocks while plag is more commonly gray; quarts is uniaxial, lacks cleavage ...

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Plagioclase Feldspar | Physical-Optical Properties ...

Moonstone is a name given to a gem material that consists of very thin, alternating layers of orthoclase (an alkali feldspar) and albite (a plagioclase feldspar). Some specimens of labradorite exhibit a schiller effect, which is a strong play of iridescent blue, green, red, orange, and yellow colors when moved under a source of incident light.

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General : Color in feldspars

 · AFAIK, there are no reports of pleochroism in feldspar and the usual sources all report plagioclase as showing none and FWIW I have never seen it.. That said the colour variation you show in your pics does look as would a single pleochroic colour change with a 90 deg axial rotation.

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Plagioclase Photos and Premium High Res Pictures

piece of raw sunstone. sunstone is a plagioclase feldspar, which when viewed from certain directions exhibits a spangled appearance. - plagioclase stock pictures, royalty-free photos & images Plagioclase feldspar, Joins a quartz vein, Rocks, mineral, igneous, New Zealand .

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(PDF) The cooling kinetics of plagioclase feldspar as ...

The cooling kinetics of plagioclase feldspar as revealed by electron-microprobe mapping. American Mineralogist, 2014. Silvio Mollo. Piergiorgio Scarlato. Gianluca Iezzi. Andrea Cavallo. E. Shahini. ... Plagioclase–melt (dis)equilibrium due to cooling dynamics: Implications for …

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Plagioclase: The mineral Plagioclase information and pictures

The Plagioclase series is a group of related feldspar minerals that essentially have the same formula but vary in their percentage of sodium and calcium. Albite and Anorthite are the end members of the series, with the intermediary minerals Oligoclase, Andesine, Labradorite, and Bytownite. The acclaimed Dana''s System of Mineralogy lists the intermediary members as individual minerals, whereas ...

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Labradorite: The gem plagioclase feldspar with play-of-color!

Plagioclase: The mineral Plagioclase information and pictures

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Feldspars Flashcards | Quizlet

plagioclase feldspars - Ca-Na alkali feldspars - Na-K in common usage, the terms alkali feldspar and K- feldspar are used interchangeably. Plagioclase Feldspar Physical Color. White. K-Feldspar Physical Color. White or Salmon Pink. Luster. vitreous, pearly. ... As the crystal grows it may change composition as it attempts to equilibrate with ...

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Feldspar

 · Feldspar is a group of minerals that are very important in rock formation, accounting for over half of Earth''s crust! There are a number of varieties that are used in jewelry. The most important are andesine, sunstone, amazonite, moonstone, and labradorite, the latter two known for their phenomenal adularescence and iridescence .

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Plagioclase

S.K. Haldar, in Introduction to Mineralogy and Petrology (Second Edition), 2020 3.5.8.6.1.2 Plagioclase feldspar series. Plagioclases are triclinic feldspars that form complete isomorphic compounds that are the final members of the Na-plagioclase albite NaAlSi 3 O 8 (Ab) and Ca-plagioclase anortite CaAl 2 Si 2 O 8 (An) (Table 3.13) albite one of four Si 4+ ions is isomorphic substituted ...

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Textural Evolution of Plagioclase Feldspar across a Shear ...

The CPOs of plagioclase feldspars have been analysed in many kinds of deformed rocks, and in high-grade metamorphic rocks the (010) planes of plagioclase grains have been found to be roughly parallel to the rock foliation (Olesen, 1987; Xie et al., 2003).

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Feldspar Gemstone Info

The alkali content in feldspar acts as a flux, lowering the glass batch melting temperature and reducing production costs. Granite, an important building material, contains 50% to 70% alkaline feldspar. Feldspars are generally light-colors, such as white, pink, tan, green or gray. The color varies due to impurities within the crystal structure.

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Incommensurate density modulation in a Na-rich plagioclase ...

slowly cooled plagioclase with compositions between ! An 46 and ! An 60 (Ribbe, 1983a), which is called Bøggild inter-growth. These exsolution lamellae are normally at a scale of hundreds of nanometers, which result in a play of light and display iridescent colors. Plagioclase feldspars with composi-

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Shock metamorphism in plagioclase and selective ...

 · INTRODUCTION. Plagioclase feldspar is the most abundant rock‐forming mineral in the crust of solid planetary bodies, including Earth, and represents up to 70% of the Moon''s crust (e.g., Papike et al. 1991) spite the abundance of plagioclase, studies of its response to shock metamorphism are limited in comparison to those of quartz or olivine (e.g., Langenhorst [] and …

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What color is plagioclase feldspar?

 · What color is plagioclase feldspar? Plagioclase Series of the Feldspar Group of Silicate Minerals. Typically white to gray, may also range from colorless, through shades of off-white, to yellowish, pink, reddish brown or nearly black. Common twinning in the crystal structure that creates fine parallel grooves or striations on some cleavage ...

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Plagioclase Meanings

Plagioclase is feldspar that contains "sodium (Na)" and "calcium (Ca)". When it contains a lot of sodium, it is called "Albite". If calcium does, it is called "Anorthite". When it is in the middle of "Albite" and "Anorthite", it becomes "Labradorite". The appearances also change …

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Gallery of Feldspars

 · Feldspars are a group of closely related minerals that together make up the majority of the Earth''s crust. All of them have a hardness of 6 on the Mohs scale, so any glassy mineral that''s softer than quartz and cannot be scratched with a knife is very likely to be a feldspar.. Feldspars lie along one of two solid-solution series, the plagioclase feldspars and the alkali or potassium feldspars.

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