Alkali feldspar examples

English examples for alkali feldspar - True granite according to modern petrologic convention contains both plagioclase and alkali feldspars. If the rock has a greater percentage of alkali feldspar, it grades into a syenite. Biotite is a common mineral in these rocks, which often contain also much quartz and alkali feldspar English examples for of alkali feldspar - If the rock has a greater percentage of alkali feldspar, it grades into a syenite. More than 90% of the total feldspar content is in the form of alkali feldspar. Kaolinization refers to the alteration of alkali feldspar into the clay mineral kaolinite in the presence of slightly acidic solutions Alkali felgspars The alkali feldspars include monoclinic feldspars (orthoclase and sanidine) and triclinic feldspars (microcline and anorthoclase). It is possible to form mixed-crystals of isomorphic replacement of Or-component and Ab-component at high temperatures Some workers (eg the Strunz classification) include barium feldspars (celsian and hyalophane), the ammonium feldspar buddingtonite and the rubidium feldspar rubicline, as alkali feldspars. Age distribution Hid The study of feldspars includes their formation con-ditions, occurrences, chemical, and physical behaviors. Alkali feldspars are solid solutions of the end-members K[AlSi3O8] (Or) and Na[AlSi3O8] (Ab). They mostly con-tain small amounts of Ca[Al2Si2O8] (An). In addition to their chemical compositions, they are characterized by th


Feldspars are a group of rock-forming aluminium tectosilicate minerals, containing sodium, calcium, potassium or barium. The most common members of the feldspar group are the plagioclase feldspars and the alkali feldspars. Feldspars make up about 60% of the Earth's crust, and 41% of the Earth's continental crust by weight. Feldspars crystallize from magma as both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock. Rock formed almost entirely of calcic p Many other examples of alkali-feldspar granite, and much of the associated mineralisation, are probably also of essentially primary magmatic origin rather than of metasomatic or hydrothermal origin as commonly interpreted. They may also be genetically unrelated to granites with which they are associated Sanidine is usually distinguished rather easily from the other alkali feldspars because it typically appears glassy—i.e., it tends to be colourless, and much of it is transparent. Microcline and orthoclase, by contrast, are characteristically white, light gray, or flesh- to salmon-coloured and subtranslucent The first is alkali feldspar and the second is plagioclase feldspar. Alkali Feldspar in Detail Alkali feldspar has the formula KAlSi 3 O 8, potassium aluminosilicate. The formula actually is a blend ranging from all sodium (albite) to all potassium (microcline), but albite is also one endpoint in the plagioclase series so we classify it there

Robert M. Hazen, in Progress in Biological Chirality, 2004 3.2 Alkali Feldspar. Feldspars, including the alkali feldspar series (Na,K)AlSi 3 O 8 and the plagioclase feldspar series (NaSi,CaAl)AlSi 2 O 8, are among the most common rock-forming minerals in Earth's crust [24, 25].These framework aluminosilicates are major constituents of most igneous rocks and they provide the principal. You Are Viewing A Blog Post. alkali feldspar examples. November 30, 2020; By ; In Studio Updates; No Comment Crypto- and microperthitic alkali feldspar were analyzed in five groups of samples: least-altered RDG, quartz monzodiorite (Phillip's Ridge), Donington Suite granite (Wirrda Well and Cape Donington) and foliated leucogranite/aplite (Cape Donington) The alkali feldspars include orthoclase, microcline, sanidine, anorthoclase, and the two-phase intermixtures called perthite. The plagioclase feldspars include members of the albite-anorthite solid-solution series. Strictly speaking, however, albite is an alkali feldspar as well as a plagioclase feldspar

alkali feldspar Examples and How to Use it - Nyanglis

  1. Feldspar sentence examples:1.the sapphires are the product of early crystallization of alkali basalt magma and intergroom with clinopyroxene, Feldspar, garnet and zircon megacrysts.2.thermodynamic and kinetic of phosphorus adsorption onto calcined Feldspar3.granitic rocks mainly consist of quartz, plagioclase and alkalin
  2. Albite (NaAlSi 3 O 8) is the sodium-rich end-member of both the alkali feldspars and the plagioclase feldspars. The semi-precious moonstone, with its characteristic bluish sheen or schiller, is an example of a perthitic alkali feldspar. A Dictionary of Earth Sciences AILSA ALLABY and MICHAEL ALLAB
  3. Alkali feldspars are the solid solution between the endmembers Or and Ab (Ribbe, 1983)
  4. Common alkali feldspars are orthoclase, microcline, adularia, and sanidine. Plagioclase feldspars are albite, oligoclase, andesine, labradorite, bytownite, and anorthite. This rock sample (alkali feldspar syenite) does not contain much more than red-colored alkali feldspar. The width of the sample from Estonia is 8 cm

are arguably the most intensively studied plutonic alkali feldspars and both provide examples of microtextures formed by volume diffusion and by multiple phases of replacement in aqueous fluids. It is important not to generalize their features too widely but we have seen similar features in many other examples of syenitic and granitic rocks Alkali fedspar syenite Syenite, from Latin Lapis Syenitis (lapis = stone), from Syene (an ancient city of southern Egypt), is a coarse-grained intrusive igneous rock of the same general composition as granite but with the quartz either absent or present in relatively small amounts (5%).The feldspar component of syenite is predominantly alkaline in character (usually orthoclase) Alkali feldspars form the main-constituents and are accompanied by aegirine-augite, riebeckite, fayalitic olivine, ilmeno-magnetite, apatite. springer Discordant U-Pb ages from an alkali - feldspar granite also constrain crystallization to ca

What does alkali-feldspar mean? Any of a series of feldspars, consisting primarily of a mixture of sodium aluminum silicate, NaAlSi3 O8 , and potassium. our results are essential to characterize and distinguish alkali feldspars on the surfaces of terrestrial planetary bodies like Mercury Mineralogists characterize alkali feldspar composition by aparameter calledNOr' which is simply the mole fraction ofpotassium inthe mineral. IfNOr=0.7, for example, a formula of Ko.7Nao.3AI~.i30g isimplied (note that Na and K always add to 1.0) Any of several feldspar minerals containing alkali metals and little calcium. Plagioclase, orthoclase and microcline are alkali feldspars We chose the Shap feldspar for our experiments because it is one of the most studied examples of commonly-occurring alkali feldspar, and its microtextural evolution during laboratory heating has..

Examples for of alkali feldspar and how to use it

  1. eral to be deposited was a reddish alkali feldspar, followed by abundant deposition of epidote and smaller amounts of pumpellyite.' More example sentences 'Of these, alkali feldspar, particularly orthoclase, is the most common.
  2. analysis on three additional feldspar samples (two perthites and a high albite) to get a mean value of E = 1.86 ± 0.03 eV. The same analysis of natural aliquots of the K-feldspar sample yields similar results, with the two highest E-values at 1.81 and 1.86 eV. The kinetic order does not systematically vary with isotherma
  3. or intrusions has been undertaken
  4. one alkali feldspar. In other plutonic igneous rocks, there may be two alkali feldspars: ortho-clase (or microcline) rich in K and albite rich in Na. Alkali feldspars of intermediate composi-tion that are cooled slowly from high temperatures may unmix or exsolve to form perthite,
  5. Most alkali feldspars are compositionally closer to Or end-member which explains why we often refer to them as K-feldspars (potassium feldspars). Microcline is a triclinic K-feldspar and has a characteristic cross-hatched tartan pattern of twinning seen with a petrographic microscope. Orthoclase and sanidine are both optically monoclinic K.
  6. groups. Here we give results only for the alkali feldspars; those for the plagioclase feldspars are quite different and have been reported elsewhere (Huntley et al. 2007). Previously, Baril (2002) and Baril and Huntley (2003b) reported phosphorescence spectra of some feldspars at room temperature and above from 1.24 to 5.5 eV (1000 to 225 nm)
Print Geology Lab Igneous Rocks flashcards | Easy Notecards

Alkali Feldspar - an overview ScienceDirect Topic

Alkali feldspar is the third most abundant mineral in Earth's crust. With the exception of rare, very rapidly cooled volcanic alkali feldspars and some near end-member crystals that grew at diagenetic temperatures, almost all natural alkali feldspar crystals exhibit various intracrystal exsolution and twin micro Basically, the two properties which make feldspars useful for downstream industries are their alkali and alumina content. On those elements we can distinguishThree families: 1) Feldspatic sand: with an alkali content (Na2O+K2O) < 6% or alumina content (Al2O3) < 8% 2) Pegmatite: with an alkali content (Na2O+K2O) >6% and alumina content (Al2O3. Feldspar Group Minerals. Feldspar is the name of a large organization of rock-forming silicate minerals that make up over 50% of Earth's crust. They are discovered in igneous, metamorphic, and sedimentary rocks in all components of the sector. Feldspar minerals have very comparable structures, chemical compositions, and bodily properties A sample from Lilla Söderby, Sweden. Width of sample 10 cm. Alkali feldspar syenite (also known as umptekite) from Sweden. Width of sample 12 cm. Nepheline monzosyenite from Sweden consisting of albite, nepheline, and mafic minerals. Such rocks rich in sodium feldspar albite are sometimes referred to as canadite. Width of sample 17 cm Pegmatite is a very coarse-grained igneous rock. Simple pegmatites are composed of large crystals of ordinary minerals. Here is a sample of alkali feldspar granite pegmatite from Northern Norway which is composed of alkali feldspar (pink), quartz (gray) and biotite (black). Width of view 50 cm

Alkali Feldspar: Mineral information, data and localities

  1. Alkali feldspars are the solid solution between the endmembers Or and Ab (Ribbe, 1983). Reitze et al. (2020) successfully applied autocorrelation technique to the alklai feldspar spectra and found.
  2. erals that contain the alkali metal elements potassium and sodium. The normal feldspar
  3. Samples: For our study, we used a natural -feldspar K sample of gem quality from Volkesfeld, Eifel, Germa-ny. This sanidine has an Al site occupancy XAl T1=0.305(2) [4]. For ordered low albite, we used a natural sample from Cazadero, California. The adularia sample is from Caoradi, Switzerland. The rthoclase o sample is from Honshu, Japan

As you remove alkali feldspar from proper granite, it becomes granodiorite and then tonalite (mostly plagioclase with less than 10% K-feldspar). Recognizing tonalite takes a close look with a magnifier to be sure that alkali feldspar is truly absent and quartz is abundant. Most tonalite also has abundant dark minerals, but this example is. Letter The elastic tensor of monoclinic alkali feldspars Naëmi Waeselmann1,*, J. Michael Brown1, Ross J. Angel2, Nancy Ross3, Jing Zhao3, and Wer- ner Kaminsky4 1Department of Earth and Space Sciences, University of Washington, 4000 15th Avenue NE, Seattle, Washington 98195-1310, U.S.A. 2Department of Geosciences, University of Padova, Via G. Gradenigo 6, I-35131 Padova, Ital ABSTRACT Phosphorus‐rich alkali feldspars were found in three peraluminous highly differentiated albite‐topaz‐Li‐mica granites in the W and S parts of the Bohemian Massif. The average contents of P2O5 in K‐feldspars (Křížovy kámen 0.57 wt%, Homolka 0.77 wt%, and Podlesí 0.83 wt%) are higher than the average contents of P2O5 in albites (Křížovy kámen 0.23 wt%, Homolka 0.23 wt. Twelve alkali feldspar specimens were selected for the investigation. They include onc albite (Ab), five anorthodases (AI, A2, A3, A4, AS)' onc maximum microcline (MM), three orthoclases (Or 1, Or 2, Or 3) and two sanidines: a high sanidine (HS) and a low sanidine (LS); the Or 1 sample is an international standar referring to an intergrowth of alkali feldspar and quartz (fig 15-15 bottom). It may be wormy or vermicular, or may occur in regular geometric patterns. Granophyric texture is an example of a eutectic texture, resulting from the simultaneous precipitation of quartz and feldspar from a melt. Identification: Microcline: Hand Sample: Cannot be.

Feldspar - Wikipedi

the alkali feldspars. Yund (1982) has reviewed pub-lished alkali self-diffusion data for the alkali feld-spars and recommends the data of Foland (1974) and Kasper (1975). Foland's data are for an ortho-clase of Orea composition and Kasper's data are for Amelia low albite. Diffusion coemcients based on the cylindrical models of Foland and Kasper ar (a) Marginal part of an alkali feldspar megacryst (sample 80C); there is a progressive change in intensity of the blue CL colour from dark to medium and light (arrows); the reaction causing the appearance of dark blue luminescence implies simultaneous carbonate crystallization; reaction rims (short arrow) are also visible on plagioclase inclusions alkali feldspar in a sentence - Use alkali feldspar in a sentence and its meaning 1. In the alkali feldspar almost pure albite domains are observed. 2. Less quartz content would lead to quartz alkali feldspar syenite . click for more sentences of alkali feldspar..

Origin of alkali-feldspar granites: An example from the

  1. of these pegmatitic feldspars are extremely complex, vary from point-to-point in the samples, and are different in several ways to the types of alkali feldspar common in normal igneous rocks. A second aim was to investigate the processes producing the perthitic intergrowths and to explore the potential of using feldspar microtextures at th
  2. g
  3. g
Studying the OU S260 Thin Rock Sections Under The Microscope

Feldspar - Identification of specific feldspars Britannic

  1. alkali feldspars from the Klokken syenite, South Finally, we caution that, when using pegmatitic Greenland. Earth and Planetary Science Letters, 109, gem-quality feldspars for diffusion experiments, 147- 167
  2. Orthoclase. Orthoclase is frequently known as potassium feldspar or K-spar, and is easily distinguished from the plagioclase feldspars in hand sample by its lack of striations. In thin section, alkali feldspar grains often look like they're sprinkled with dirt (PPL) or tiny confetti (XPL). You can find the explanation on the alkali feldspar page
  3. eralization have porphyritic textures with phenocrysts of alkali feldspar, plagioclase, biotite, and very rare amphibole in a fine-grained feldspathic groundmass. springer
  4. erals (such as alu
  5. Feldspars are major components of terrestrial planetary surfaces. For future space application and the setup of a comprehensive reference database, Na- and K-rich alkali feldspars, NaAlSi 3 O 8 - KAlSi 3 O 8 , have been investigated by infrared reflectance spectroscopy. We related the feldspar spectra to the chemical composition and state of Al,Si order/disorder
  6. The Nepheline and Associated Alkali Syenites of Eastern Ontario . he potash in the Indian feld-spar is 5 :1, while in the Canadian and Russian occurrences the soda isonly slightly in evcess, and in the separated feldspar is practically thesame
  7. matrix) against ionic radius of the alkali and alkaline earth elements in forty-four alkali feldspars from rhyo- lites and trachytes show two kinds of diagram, one for homogeneous alkali feldspars with a single peak, and the other for cryptoperthites with a wide spread of points

Feldspar Distinctions, Characteristics & Identificatio

alkali translate: 鹼;強鹼. Learn more in the Cambridge English-Chinese traditional Dictionary QAPF means Quartz, Alkali feldspar, Plagioclase, Feldspathoid. QAPF is the abbreviation for Quartz, Alkali feldspar, Plagioclase, Feldspathoid. Search for abbreviation meaning, word to abbreviate, or category. Shortcuts for power users - examples. Abbreviation meaning - COB means. To abbreviate - Management abbreviated Alkali definition: An alkali is a substance with a pH value of more than 7. Alkalis form chemical salts when... | Meaning, pronunciation, translations and examples The K-feldspars or alkali felspars: Microcline, (Potassium aluminum silicate) Sanidine, (Potassium sodium aluminum silicate) Orthoclase, (Potassium aluminum silicate) The feldspars are a group of minerals that have similar characteristics due to a similar structure. All feldspars have low symmetry, being only monoclinic, 2/m, to triclinic, bar 1

Geology - rocks and minerals

A fragment of opaque, pale grey alkali feldspar. Two sets of good cleavage at right angles, with a pearly lustre on the cleavage faces. M402 Alkali feldspar, orthoclase. Shap, Westmorland. Porphyritic granite. Large phenocrysts of pink feldspar, two sets of cleavage at 90°, simple twinning. Also white plagioclase feldspar, quartz and biotite The feldspar minerals are the most common minerals in the earth's crust. They are aluminosilicates of potassium, calcium, and sodium. The feldspars are divided into two groups, the alkali feldspars and the plagioclase feldspars. The plagioclase series is a solid solution series. The alkali feldspars are mainly potassium feldspar and albite Alkali Feldspars (K,Na)AlSi 3 O 8. As an alkali feldspar cools from high temperature to lower temperature, the crystal structure changes from that of sanidine, which is monoclinic, through orthoclase, also monoclinic, but with a different crystal structure than sanidine, to microcline, which is triclinic

Feldspar - an overview ScienceDirect Topic

For the entire alkali feldspar series, Σt₁ (total Al content in the T₁ sites, a quantitative measure of structural state or Al,Si long-range ordering) can be closely estimated from X Or (mole fraction of KAlSi₃O₈) and Y x (one half of the optic axial angle 2V x) by use of a simple determinative diagram based on the model Σt₁ = (b₀. This sample is quartz alkali feldspar syenite from Estonia. Width of sample 8 cm. Texture. Granite is a coarse-grained igneous rock with average grain size ranging from 1 to 25 millimeters 1. These rocks crystallize from a very slowly cooling magma within the crust where they are well insulated. Time gives crystals a chance to grow served features of alkali feldspar age spectra and their asso- ciated Arrhenius plots. Because these domains contain a range of closure temperatures, LOVERA et al. (1989) found that a single K-feldspar sample may reveal a broad segment of a cooling history, rather than the single datum usually expected

alkali feldspar examples - thewadestudio

LOW TEMPERATURE ALKALI FELDSPAR SERIES BY S. V. LAKSHMI NARAYAXA R-\.0 (lndian Institute of Technology, 1\hargapur, India.J A b s t r a c t. Mixtures of microcline and low albite containing different pro­ portions of the two feldspars have been heated at 1025° C and the shift of d2c,jlines has been used to evaluate the extent of homogenisation structure of alkali feldspar megacrysts and give evidence for their origin. Since the submicron scale mineralogy of the abundant alkali feldspar megacrysts from the Papuk Mt. was unknown this paper provides Geologia Croatica. 57/2 149-158 7 Figs. 2 Tabs. ZAGREB 2004 Key words: Microstructure, Modulation, Alkali feld The volume ratio of alkali feldspar in the C11 sample of granodiorite is much larger than that in the C13 sample of tonalite (Fig. 1), although alkali feldspars occur intersti-tially in both the samples. There is a large difference be-tween the appearances of the C13 and C11 alkali feld Mineralogy of Alkali-feldspar-syeniteHide. Essential minerals - these are minerals that are required within the classification of this rock: Feldspar > Alkali Feldspar: A subgroup of the Feldspar Group, poor in calcium, and mostly rich in potassium. Non-essential minerals - these minerals are common, sometimes major components, but are not. Compositions of major elements in common feldspars can be expressed in terms of three endmembers: potassium feldspar (K-spar) endmember K Al Si 3 O 8, albite endmember NaAlSi 3 O 8, anorthite endmember CaAl 2 Si 2 O 8. Solid solutions between K-feldspar and albite are called alkali feldspar


Rare earth element geochemistry of feldspars: examples

Shock barometer using cathodoluminescence of alkali feldspar Masahiro Kayama,1 Hirotsugu Nishido,2 Toshimori Sekine,1 Tadahiro Nakazato,2 Arnold Gucsik,3,4 and Kiyotaka Ninagawa5 Received 14 November 2011; revised 30 July 2012; accepted 2 August 2012; published 18 September 2012 ALEX STREKEISENAlkali feldspar syenite. Alkali Fedspar Syenite Syenite, from Latin Lapis Syenitis lapis stone of Syene, from Syene an ancient city of southern Egypt, is a coarsegrained intrusive igneous rock of the same general composition as granite but with the quartz either absent or present in relatively small amounts 5.The feldspar component of syenite is predominantly alkaline in.

photomicrographs - igneousOlivine, Cordierite and Feldspar

feldspar Properties, Uses, Types, & Facts Britannic

ture of 765 °C, values which are considered representative for MER vol- canics (Gleeson et al., 2017; Webster et al., 1993). We assume a density contrast between melt and crystals of 170 kg/m 3 , based on the domi- nance of alkali feldspar (2550 - 2630 kg/m 3 ) and quartz (2650 kg/m 3 ), and a melt density of 2390 kg/m 3 (following Bottinga & Weill, 1970) Fast vs Slow Cooling and Feldspar Composition Fast cooling in the alkali feldspar system results in growth of a one phase feldspar. These feldspars are the high feldspars, with disordered structures. Feldspars that grow in slow to very slow cooling systems, at low temperatures, separate into two phases: these are low feldspars Any of a large group of rock-forming minerals that, together, make up about 60% of the earth's outer crust. The feldspars are all aluminum silicates of the alkali metals sodium, potassium, calcium and barium. Feldspars are the principal constituents of igneous and plutonic rocks

Andesite - WikipediaPorphyry - Igneous Rocks

T1 - Quantitative analysis of alkali feldspar minerals using Rietveld refinement of X-ray diffraction data. AU - Shim, Sang Heon. AU - Kim, Soo Jin. AU - Ahn, Jung Ho. PY - 1996. Y1 - 1996. N2 - Microcline + albite and albite + quartz standard mixtures were quantitatively analyzed using Rietveld refinement to investigate the reliability of the. Quantitative phase analysis of a perthite specimen using the Rietveld method resulted in very accurate values for the mineral proportion and unitcell parameters of the constituent alkali feldspars, demonstrating the power of the Rietveld method to analyze multiphase samples Sanidine is stable at the highest temperatures, and microcline at the lowest. Perthite is a typical texture in alkali feldspar, due to exsolution of contrasting alkali feldspar compositions during cooling of an intermediate composition. The perthitic textures in the alkali feldspars of many granites can be seen with the naked eye Feldspars are often twinned or multiply twinned in addition to perthitic and antiperthitic exsolution in alkali feldspars addressed above (Deer et al. 2001). Therefore, the sample suite included twinned and exsolved specimens as well as single crystals (Table 1 ) Alkali feldspar granite, some varieties of which are called red granite, is a felsic igneous rock and a type of granite rich in the mineral potassium feldspar. It is a dense rock with a phaneritic texture. The abundance of K-spar gives the rock a predominant pink to reddish hue; peppered with minor amounts of black minerals