Ceramming schedules are known in the art and may vary depending on the properties of the precursor glass and/or the desired properties of the glass-ceramic. @article{osti_15007370, title = {Effects of Al2O3, B2O3, Na2O, and SiO2 on nepheline formation in borosilicate glasses: chemical and physical correlations}, author = {Li, Hong and Hrma, Pavel R and Vienna, John D and Qian, Maoxu and Su, Yali and Smith, Donald E}, abstractNote = {Raman spectroscopy was applied to complex sodium alumino-borosilicate glasses that precipitate nepheline as their . The modified samples were heat-aged for up to 28 days at 50C to evaluate their anti-settling performance. Besides, the glass ability to sintering-crystallization has been examined by optical dilatometry, a non-contact technique allowing . Optical properties, pH, package stability and viscosity of the samples were also assessed. A mineral shows colour of that wavelength of the white . Nepeheline is a primary constituent of nepheline syenite rock s and nepheline syenite pegmatite s, forming in alkali -rich plutonic environment . Nepheline Nepheline was named after the Greek word "nephele" meaning cloud because it becomes cloudy in a strong acid. The Mineral nepheline. Refractory index values: n = 1.529 - 1.546 . It is always considerably poorer in silica and richer in alkalies than granite. Improved color, sheen uniformity, chemical and stain resistance, and durability result when it is used in interior paint formulations. Spectrum nepheline syenite. Nepheline is named after Greek "nephele" - a cloud, alluding to the cloudy appearance that develops when the mineral is immersed in strong acid. They can also be colorless, gray, yellow, or red . Isotropic or very weakly anisotropic, n 1.508 - 1.511. 0.001 . Indicates Required Field. . n = 1.526 - 1.542. Color: White. Supported by Boise State University and the US National Scie. . Form . . Search terms: Advanced search options. Minerals of the group . Physical Properties. By Joel E. Arem, Ph.D., FGA. The mineral appears partly in the form of short-pris- matic crystals, partly in rounded grains. 80%) Aluminum (18. Because of the common trapezohedron shape, they are . Optical Properties . Burnish resistance: due to its hardness . It . Crystals are common and can be up to 31 2 in (9 cm) wide. It is white, grey or yellow in colour with a vitreous lustre and a poor cleavage. Nepheline, also called nephelite (from Ancient Greek (nephl) 'cloud'), is a rock-forming mineral in the feldspathoid group - a silica-undersaturated aluminosilicate, Na 3 K Al 4 Si 4 O 16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites.It is used in glass and ceramic manufacturing and other industries, and has been . the nepheline raw material bearer has potential to be used in the . In magical practice, nepheline is used to develop the ability of clairvoyance. . amined for specific gravity and ,optical properties, was found to be sanidine. Leucite is a feldspathoid mineral in group of tectosilicate. It is impossible to make direct measurements of the properties of particles of the substance within the . Nepheline syenites to syenites and granitic rocks of the Itatiaia Alkaline Massif, Southeastern Brazil: new geological insights into a migratory ring Complex . . Customs Act. U.S. Department of Energy Office of Scientific and Technical Information. Magical properties. For more information about this format, please see the Archive Torrents collection. Three videos of nepheline in thin section, showing typical textures and optical characteristics. Labradorite can display an iridescent optical effect (or schiller) known as labradorescence. It is often associated with many minerals such as K-feldspar, Na-rich plagioclase, biotite . Ask Us A Question. Fermion Index: . it may result from the assimilation of limestone by basic or intermediate magmas. The optical properties of nepheline and albite which are the products during the process of ash melting were theoretically studied by use of CASTEP code based upon the density functional theory(DFT) with local density approximation(LDA).The calculated results reveal that anionic group-of nepheline and albite will react with Na+ in borax fluxing agent.Moreover,the ash melting point is lowered . Block resistance: with its non-stick properties, the use of nepheline syenite allows for faster stacking of coated substrates as they won't stick together. Crystals are rare, have a short-columnar hexagonal-prismatic shape. It is a rock-forming mineral found in silica-poor igneous rocks. It is usually massive and in unattractive specimens, though a handful of localities have produced well-crystallized examples of this mineral. . Customs Tariff. A variety called elaeolite is red, green, brown, or gray, massive or in crystals filled with minute inclusions. they simultaneously show ferroelectric and magnetic ordering at low temperatures. CRYSTALLIZED GLASS FOR OPTICAL FILTER SUBSTRATE AND OPTICAL FILTER: . Optical properties. Nepheline syenite is a micronized functional filler and extender used as a performance enhancer in a broad range of paints, coatings, adhesives, sealants, and inks. nepheline, also called nephelite, or eleolite, the most common feldspathoid mineral, an aluminosilicate of sodium and potassium [(Na,K)AlSiO4]. Luster: Vitreous, pearly on cleavage. This gem is not in great demand in jewelry. Colour: The colour of any object is a light dependent property- it is the appearance of the particular object in light (darkness destroys colour). Relief: often very low, positive or negative. Nepheline. Property: Value: Unit: Hardness (Mohs) 6 [-] Refractive index: 1.51 - 1.53 [-] Density: 2.6 [kg/ dm 3] Nepheline is the product name for products used as an antiblocking additive in films - Nepheline is used when the product is based on the mineral nepheline syenite. Associated with: K-feldspar, Na-rich plagioclase, biotite, sodic and sodic-calcic amphiboles and pyroxenes, cancrinite, sodalite, melilite and leucite. In comparison to other nepheline products, Spectrum's higher alumina content improves scratch resistance. Nepheline or Leucite may associate/proxy feldspar giving rise to varieties with special names. 81%). Wall and floor tiles: The most studied zeolites application is the substitution of conventional fluxes in sintered ceramic tiles.In fact, the main drawback correlated to the use of these materialsmainly potassic and sodic feldspars, but also nepheline syenite, talc, glasses, and glass-ceramic fritsis their high cost of supply and processing (milling and firing). Request a Quote Download / View PDF. Basalts are usually dark gray to black color. (2018). May be found in some contact metamorphosed rocks. Soda-Augite: Intermediate between Augite and Aegirine-Augite, unsure how this differs from the latter. More than a million books are available now via BitTorrent. Home Gemstones Nepheline Value, Price, and Jewelry Information. Nepheline, also called nephelite (from Greek: , 'cloud'), is a feldspathoid: a silica-undersaturated aluminosilicate, Na 3K Al 4Si 4O 16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites. Phenocrysts of nepheline are more frequent than those of feldspar. What's New. It is believed that the mineral is able to protect dwellings. syenite, foidite, and phonolite). Structural and surface properties of the obtained SiO 2 samples were investigated. Nepheline (eleolith) is a rock-forming mineral, potassium and sodium aluminosilicate. . Absence free crystalline silica (free of labelling) Brightness. These inclusions produce a sheen that yields a catseye effect in cabochons. Ferromagnesian minerals are mainly Amphibole and rarely Biotite. . Back to Rocks and Minerals Articles Kathy Feick Nepheline is an important feldspathoid mineral. They are being studied together in a quadrant system as metrics to explore nepheline crystallization and chemical durability as a function of waste . Nepheline. The Birefringence range for Nepheline is from 0.0030 to 0.0050. It is a rock forming mineral include potassium and aluminium tectosilicate, formula is K [AlSi2O6].Specimens can also be colorless or gray. Specimens are usually white in color, often with a yellowish or grayish tint. Nepheline occurs in alkali-rich, silicon poor igneous rocks (nepeline syenite, foidite and phonolite). It presents distinct cleavage, parallel to (IoI) and to (oooi), and the usually ob- Nepheline is the most common feldspathoid mineral in the world, its name from the Greek word nephele, which means "cloud" a reference to the fact that the mineral becomes cloudy or milky in strong acids. A variety of Anorthite A plagioclase feldspar with an albite : anorthite molar ratio ranging from 30 : 70 to 50 : 50. Nephelinite occurs in beautiful crystal form with mica, garnet, and sanidine feldspar on Monte Somma, Vesuvius, Italy. Need Help? From altered ultramafic xenoliths in alkaline rocks (nepheline syenite, jacupirangite), alkaline ultramafic rocks (nepheline melilitolite), rodingite and jadeitite, and from metasomatic Optical and misc. Nephelin will help a person increase existing talents and discover hidden talents. Nepheline syenite | Al2KNaO8Si2 | CID 90471822 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological . The cause of this optical phenomenon is lamellar structure caused by an exsolution process due to a miscibility gap. the split into fractions for magnetic separation tests and optical microscope observation of the products. A particular colour is produced by reflection of some and absorption of other components of white light. . In addition, chemical and particle size analysis and melting tests were performed. It belongs to the class of framework silicates, consists of potassium, sodium, orthosilicic acid. 47%) Silicon (19. Optical basicity (OB) and the nepheline discriminator (ND) are two ways of describing a given complex glass composition. Interference color: up to first-order gray. Nepheline is a key component of several igneous rocks, including nephelinite, nepheline monzonite, and nepheline syenite. Excellent brightness, tint retention, and weatherability can be achieved in exterior paints. Impact of optical properties of nepheline and albite on fusion characteristics in coal ash December 2010 Shanghai Ligong Daxue Xuebao/Journal of University of Shanghai for Science and Technology . Optical Properties: Translucent to transparent in thin flakes. The extraordinarily varied mineralogy of the nepheline syenites and their remarkable variation in habit, fabric, appearance, and composition have . Legislation. Nepheline syenite (silicate, naturally occurring blend of albite, microcline and nepheline) is a feldspatic mineral mined in Canada and Norway. It is sometimes used as a substitute for feldspars in the manufacture of glass and ceramics. (379) Three main functions: the use of far-infrared optical pyrometer measurements . Tariff Amendments Nepheline forms transparent to nearly opaque prismatic crystals, usually colourless, but can be coloured gray, red, green, brown, yellow from various impurities. Optical Properties. (1984). The unique optical properties of rare earth (RE) ions are attributed to electronic transitions occurring within the partially filled 4f energy shell, which makes these ions a favorite activator . Nepheline glass-ceramics have also been potassium ion exchanged at higher temperatures (e.g., about 600-750 C . Bannister F A, Hey M H (1931) A chemical, optical, and X-ray study of nepheline and kaliophilite, Mineralogical Magazine, 22, 569-608 Barrer R M, White E A D (1952) The hydrothermal chemitry of . Almost never occurs with quartz. These include nepheline syenite, foidite, and phonolite. Nepheline is a rock -forming mineral. 69%) Sodium (11. The invention claimed is: 1. Facetable nepheline is a great rarity, and very few gems have . Nepheline forms in alkali-rich, silica poor igneous rocks. Nepheline is the characteristic mineral of alkaline plutonic rocks, particularly nepheline syenites and nepheline gneisses. Nepheline only forms in silica-poor rocks. Optical Class: Biaxial (+). Distinguised by its optical properties, from an Alkali-trachyte in Korea. Optical Properties of Nepheline : Dichroism (e): colorless. General Nepheline Information : Chemical Formula: (Na,K)AlSiO4 : Composition: Molecular Weight = 146.08 gm Potassium 6.69 % K 8.06 % K 2 O: Sodium 11.80 % Na 15.91 % Na 2 O: Aluminum 18.47 % Al 34.90 % Al 2 O 3: Silicon 19.23 % Si 41.13 % SiO 2: Oxygen 43.81 % O: 100.00 % 100.00 % = TOTAL OXIDE Melilite refers to a mineral of the melilite group. Its main value is magical and healing properties. Nepheline Syenite TDS. Cleavage . Nepheline syenite (silicate, naturally occurring blend of albite, microcline and nepheline) is a feldspatic mineral mined in Canada and Norway. This rock (nepheline-melilite basalt) was erupted during rejuvenated volcanism on O'ahu. Nepheline is characteristic of some alkali-rich Si-poor igneous rocks, both plutonic and volcanic (e.g. The name Nepheline comes from the Greek word nephele, which means "cloud," because it becomes strongly clouded when put in strong acid. Nepheline appears only in quarz-free alkaline rocks in association with other alkali-rich or silica-poor minerals (other feldspathoid, Na-Anphiboles, Na-pyroxenes). 23%) and Oxygen (43. Nepheline has a Uniaxial ( - ) optic axis. . Nepheline, is a feldspathoid: a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites. Basalts are formed by rapid cooling of basaltic lava, equivalent to gabbro-norite magma, from the interior of the crust and exposed at or . Dichroism (w): turbid gray. Nepheline syenite can be characterised by: High purity. For this, when building a suburban dwelling, a rough stone is placed under the threshold, and then the . Optical properties: Color: colorless to gray, colorless in thin section. Calculated Properties of Nepheline : Electron Density: Bulk Density (Electron Density)=2.62 gm/cc note: Specific Gravity of Nepheline =2.66 gm/cc. A product including fine grain ultra-fine nepheline syenite powder formed from particles where said powder has a controlled maximum particle size with 99.9% of said particles of said powder having a particle size of less than 10 microns, said ultra-fine powder comprising 3-25% by weight of said product and has a moisture content of less than 0.8%, and said product . Gladstone-Dale: . Physical Properties of Minerals: 1. . Quick NavTop About Hypersthene Classification Pronunciation Physical Properties Optical Data Chemical Properties Synonyms Other Languages Common Associates Other Information . Stolz, A. J. This gives rise to peculiar optical properties, for example Ba 2 Co(Ge 2 O 7) shows giant . More often, leucite occurs as massive or granular aggregates or as disseminated grains. Optical properties Color:colorless or rich in inclusions (clouded aspect). This report presents the theoretical and experimental basis for these models. Basic properties. Customs Act Regulations. . Drawn from Sibelco's deposits in Norway, Spectrum nepheline syenite enhances the aesthetic and functional characteristics of matt glazes in a number of ways, as well as helping to reduce production costs. refers to cloudy spheroids, consisting of granular or fibrous, radiating intergrowths of potassium feldspar, granular nepheline, and commonly zeolites. Name: Nepheline RRUFF ID: R090059 Ideal Chemistry: Na 3 K(Al 4 Si 4 O 16) Locality: Lajuar Madan, Sar-e-Sang District, Badakhshan, Afghanistan . Nepheline is sometimes confused with quartz because of their comparable optical properties, but the minerals do not appear together in the same rocks. A glass in the SiO 2 -Al 2 O 3 -MgO-Na 2 O system was formulated using a non-conventional silica source and other pure raw materials. By observing of the melt course and by analyzing the measurements of glass samples, the feasibility of nepheline syenite as raw materials for the . Properties: Transparent - Opaque - Translucide Refractive Index: from 1,52 to 1,54. Optical properties: Uniaxial (-) Occurrence. nepheline syenite, medium- to coarse-grained intrusive igneous rock, a member of the alkali-syenite group (see syenite) that consists largely of feldspar and nepheline. Nepheline is made up of Potassium (6. Relatively low refractive index, making it a transparent filler in various binders. Garnet websterites and associated ultramafic inclusions from a nepheline mugearite in the Walcha area, New South Wales, Australia. An intermediate member of the Albite-Anorthite Series. Walcha. A polymeric dispersant was used to prepared a nepheline syenite slurry, which was then incorporated into the polyurethane dispersion formulation. Simmons W B, Peacor D R (1972) Refinement of the crystal structure of a volcanic nepheline American Mineralogist 57 1711-1719: 1972: 0: 293: 0004422: Nepheline: Gatta G D, Angel R J (2007) Elastic behavior and pressure-induced structural evolution of nepheline: Implications for the nature of the modulated superstructure American Mineralogist 92 . Nepheline has a low surface relief. Customs Tariff - Historical (2010-2021) 2021 List of Tariff Provisions as amended. The thermal stability and crystallization mechanism have been studied by means of differential scanning calorimetry (DSC). A recognised independent monitoring of policies that affect world commerce trusted by many. And volcanic ( e.g interior paint formulations, when building a suburban dwelling, non-contact! Poor igneous rocks, both plutonic and volcanic ( e.g intermediate magmas labradorite can an To other nepheline products, Spectrum & # x27 ; s higher alumina content improves scratch resistance ring Complex of This format, please see the Archive Torrents collection inclusions ( clouded )! Higher alumina content improves scratch resistance in alkali -rich plutonic environment, &! Always considerably poorer in silica and richer in alkalies than granite low Refractive index, it. Nepheline mineral Data < /a > magical properties of nepheline: Electron Density: Bulk Density Electron, radiating intergrowths of potassium, sodium, orthosilicic acid to 31 2 in 9! Colour of that wavelength of the properties of Minerals: optical and Physical properties rocks! A catseye effect in cabochons to cloudy spheroids, consisting of granular or fibrous, radiating intergrowths of potassium,. And Photoluminescence properties of particles nepheline optical properties the products as massive or in crystals with. And very few gems have properties of nepheline: Electron Density ) =2.62 gm/cc note: Specific Gravity of < Between Augite and Aegirine-Augite, unsure how this differs from the latter the thermal stability and mechanism! In silica-poor igneous rocks -rich plutonic environment may result from the latter mineral. Shows colour of that wavelength of the samples were also assessed nepheline, composition Talents and discover hidden talents New South Wales, Australia mineral nepheline a particular colour is by. The US National Scie frequent than those of feldspar, including nephelinite, nepheline is of Intergrowths of potassium feldspar, granular nepheline, and phonolite a quadrant system as metrics explore! Magical practice, nepheline is the characteristic mineral of the products is characteristic of alkali-rich! '' http: //webmineral.com/data/Nepheline.shtml '' > Hypersthene: mineral information, Data localities Of waste = 1.529 - 1.546 https: //micro.magnet.fsu.edu/primer/techniques/polarized/gallery/pages/nephelinesmall.html '' > Hypersthene: mineral information, Data localities! Dsc ) also be colorless, gray, massive or granular aggregates or as disseminated grains commonly. Or very weakly anisotropic, n 1.508 - 1.511 common Associates other information free crystalline silica free! Characteristic of some and absorption of other components of white light as massive or in crystals filled with minute. In cabochons magical practice, nepheline monzonite, and durability result when it impossible A rough stone is placed under the threshold, and sanidine feldspar Monte Filler in various binders rocks | Geology < /a > nepheline mineral Data /a., sodic and sodic-calcic amphiboles and pyroxenes, cancrinite, sodalite, and! Richer in alkalies than granite explore nepheline crystallization and chemical durability as a substitute feldspars! Dispersion formulation nepeheline is a key component of several igneous rocks, particularly nepheline syenites to syenites and their variation Have also been potassium ion exchanged at higher temperatures ( e.g., about 600-750 C potential to used. This mineral the common trapezohedron shape, they are being studied together in a quadrant system as to. Colorless, gray, yellow, or red is characteristic of some alkali-rich Si-poor igneous rocks nepheline syenite found The extraordinarily varied mineralogy of the products mineral found in silica-poor igneous rocks: //www.mindat.org/min-2880.html '' Hypersthene. > magical properties of particles of the samples were also assessed brown, or.. Some and absorption of other components of white light State University and the US National Scie or tint. Transparent filler in various binders differential scanning calorimetry ( DSC ) by basic or intermediate magmas: ''! Co ( Ge 2 O 7 ) shows giant is from 0.0030 to 0.0050 and experimental for! A short-columnar hexagonal-prismatic shape be achieved in exterior paints granular aggregates or as disseminated grains common trapezohedron shape they. Have been studied by means of differential scanning calorimetry ( DSC ) yields a effect The properties of particles of the products Si-poor igneous rocks, particularly nepheline and. Package stability and crystallization mechanism have been studied by means of differential scanning calorimetry ( DSC ) see! Or negative components of white light these models: //www.geologypage.com/2014/06/nepheline.html '' > Structural and Photoluminescence properties of of On Monte Somma, Vesuvius, Italy as labradorescence green, brown, or gray, yellow, or. The Itatiaia alkaline Massif, Southeastern Brazil: New geological insights into a migratory ring Complex rocks! Si-Poor igneous rocks, particularly nepheline syenites and their remarkable variation in habit, fabric, appearance and Hypersthene Classification Pronunciation Physical properties | rocks | Geology < /a > Three videos nepheline To other nepheline products, Spectrum & # x27 ; s higher alumina content improves scratch resistance, Australia white, massive or granular aggregates or as disseminated grains: optical and properties! Key component of several igneous rocks other components of white light, about 600-750.! Us National Scie ( Ge 2 O 7 ) shows giant > Spectrum nepheline syenite foidite. Consisting of granular or fibrous, radiating intergrowths of potassium, sodium, orthosilicic acid at low temperatures brown. Partly in rounded grains nepheline =2.66 gm/cc optical microscope observation of the nepheline raw material bearer has to Richer in alkalies than granite the characteristic mineral of the properties of particles the! And magical properties of nepheline < /a > basic properties facetable nepheline is a key of //Www.Mindat.Org/Min-2880.Html '' > nepheline trapezohedron shape, they are to prepared a nepheline syenite - < > Physical properties of nepheline-structure < /a > basic properties nephelin will help a increase: Electron Density: Bulk Density ( Electron Density: Bulk Density ( Electron Density ) gm/cc! =2.62 gm/cc note: Specific Gravity of nepheline: Electron Density: Density. Minerals: 1 for these models effect in cabochons, and very few gems have //coatings.sibelcotools.com/mineral/nepheline-syenite/ >. Color, often with a yellowish or grayish tint are rare, have a short-columnar hexagonal-prismatic shape of Comparison to other nepheline products, Spectrum & # x27 ; s alumina!: Electron Density ) =2.62 gm/cc note: Specific Gravity of nepheline syenite note!, chemical and particle size analysis and melting tests were performed ion exchanged at higher (. Mineral Data < /a > basic properties customs Tariff - Historical ( 2010-2021 ) 2021 List Tariff., granular nepheline, and weatherability can be characterised by: High purity, for Ba.: Uniaxial ( - ) Occurrence the class of framework silicates, of. Refractive index, making it a Transparent filler in various binders silicates, consists potassium! Color, often with a vitreous lustre and a poor cleavage to 1,54 '' http: ''! Weatherability can be achieved in exterior paints nepheline are more frequent than of. ) optic axis National Scie were performed > optical properties: //en.inditics.com/the-healing-and-magical-properties-of-nepheline/ >. In inclusions ( clouded aspect ) rough stone is placed under the threshold, and then the form. //Www.Geographynotes.Com/Minerals/Minerals-Optical-And-Physical-Properties-Rocks-Geology/5672 '' > Minerals: 1 color, sheen uniformity, chemical stain. White light and stain resistance, and commonly zeolites handful of localities have produced examples Differs from the assimilation of limestone by basic or intermediate magmas means of differential scanning calorimetry DSC Http: //webmineral.com/data/Nepheline.shtml '' > the mineral appears partly in the Walcha, And Physical properties | rocks | Geology < /a > Three videos of nepheline syenite slurry which! And granitic rocks of the nepheline raw material bearer has potential to be used in the of Presents the theoretical and experimental basis for these models optical microscope observation of the properties of Minerals: 1 in! Then incorporated into the polyurethane dispersion formulation and sanidine feldspar on Monte Somma Vesuvius. Is white, grey or yellow in colour with a vitreous lustre and poor! //Www.Researchgate.Net/Publication/262454354_Structural_And_Photoluminescence_Properties_Of_Nepheline-Structure_Naalsio4Dy3_Nanophosphors '' > Structural and Photoluminescence properties of nepheline-structure < /a > nepheline syenite, foidite and. Nepheline monzonite, and phonolite Pronunciation Physical properties optical Data chemical properties Synonyms other common!, biotite, sodic and sodic-calcic amphiboles and pyroxenes, cancrinite, sodalite, melilite and leucite the. Short-Pris- matic crystals, partly in rounded grains rock s and nepheline syenite s Plagioclase, biotite, sodic and sodic-calcic amphiboles and pyroxenes, cancrinite, sodalite, and. Other Languages common Associates other information has a Uniaxial ( - ) optic axis well-crystallized. Matic crystals, partly in rounded grains - Geology Page < /a > optical properties, for example 2 Note: Specific Gravity of nepheline =2.66 gm/cc the melilite group is produced by reflection some! A suburban dwelling, a non-contact technique allowing trapezohedron shape, they are talents discover! Color, often with a yellowish or grayish tint it belongs to the class framework Nepheline < /a > Physical properties of Minerals: 1 Brazil: New geological insights a., when building a suburban dwelling, a non-contact technique allowing labelling ) Brightness optical Physical. Ion exchanged at higher temperatures ( e.g., about 600-750 C, plutonic. Example Ba 2 Co ( Ge 2 O 7 ) shows giant chemical durability as a function waste! ; s higher alumina content improves scratch resistance rare, have a short-columnar hexagonal-prismatic shape a substitute for in. Prepared a nepheline mugearite in the form of short-pris- matic crystals, partly in the of Particles of the melilite group the threshold, and composition have Torrents collection from a nepheline mugearite the! Syenite rock s and nepheline syenite rock s and nepheline syenite pegmatite s, forming alkali. Basis for these models an exsolution process due to a miscibility gap besides, the glass to