length slow, riebeckite length fast. … Distinguished from other Glaucophane is defined as a member of the glaucophane group with Mg>Fe 2+ in the C 2+ position and (OH) in the W position. Click on the image to see a pleochroism rollover. Relief: High positive Habit/Form: Kyanite commonly forms elongate bladed or columnar crystals that may appear to be bent. from other amphiboles. Glaucophane is also found in eclogites that have undergone … Mineral Group: Amphibole (alkali) group: Fe 2+=(Fe 2+ + Mg) < 0.5; Fe 3+=(Fe 3+ + Al vi ) < 0.3; (Na + K)A < 0.5; NaB ¸ 1.34. light. When the stage is lowered in plane … Co.; in the Kodiak Islands, Alaska, USA. & Series: Forms a series with ferroglaucophane. Click on the image to see a larger image with a rollover of cross polars. Roll over image is the same photomicrograph in cross polarized Glaucophane can also be massive, fibrous, or granular. Its glaucophane's color that gives this facies its name. ... 48 Lawsonite Lawsonite, pale brownish, with glaucophane, chlorite and white mica, in blueschist. In Japan, at Ubuzan, … The Glaucophane mineral is named after two Greek words: glaukos, which means “bluish green”; and phainesthai, which means “to appear.” Specimens can be gray, lavender blue, or bluish black. A blue sodic amphibole, glaucophane has moderate relief and shows the typical cleavage of the amphiboles, intersecting on the rhombic basal sections at 60°/120°. There is no twinning in glaucophane. Pleochroic in various shades of green and brown. Add tags Comment Rate. Glaucophane in Turkish blueschist Glaucophane in Greek blueschist (the two samples on the left) Fine-grained blueschist Medium-grained blueschist Garnet-studded retrograde blueschist after eclogite. It is rarely fibrous. Glaucophane, common amphibole mineral, a sodium, magnesium, and aluminum silicate that occurs only in crystalline schists formed from sodium-rich rocks by low-grade metamorphism characteristic of subduction zones. Characteristic of the blueschist facies, in The pleochroism is violet (g), blue (b) and colorless (a). Glaucophane crystallizes in the monoclinic system. (blue tourmaline is darkest w/ c-axis perpendicular to vibration direction cross polars. This is "glaucophane in thin section FKM-194 XP" by rockPTX on Vimeo, the home for high quality videos and the people who love them. Significant deposits have been discovered in Greece (Cyclades Islands, Syra Island), Italy (St. Marcel, Val d'Aosta, Piollore), Wales (Anglesey), Australia, Japan, and the US (Kodiak Islands, California). This glaucophane is in fact the crossite variety. ... Compagnoni, R., Engi, M., and Regis, D. (2014) Valle d’Aosta section of the Sesia Zone: multi-stage HP metamorphism and assembly of a rifted continental … Chlorite: Property: Value: Comments: Formula (Mg, Al, Fe) 3 (Si,Al) 4 O 10 (OH) 2. Alex Strekeisen - I vetrini della mia fantasia. Glaucophane is characteristically pleochroic in shades of blue and purple. At St. Marcel, Val d’Aosta, and Crystals are slender, often lathlike prisms, with lengthwise striations. Cleavage: Perfect parallel to {100}, less … Darker with increasing Fe content. Blue pleochroism in thin section/grain mount distinguishes from other amphiboles. Blue in color under regular lighting, and often found in differing shades Glaucophane has length slow, riebeckite length Glaucophane in Turkish blueschist Glaucophane in Greek blueschist (the two samples on the left) Fine-grained blueschist Medium-grained blueschist Garnet-studded retrograde blueschist after eclogite. This mineral exhibits a characteristic blue color with distinct pleochroism from colorless to lavender blue when viewed in thin section by plane-polarized light. Further Reading. Plane-polarised light, field of view 1 mm. Distinct pleochroism: X= colorless, pale blue, yellow; Y= lavender-blue, bluish green; Z= blue, greenish blue, violet. Plane-polarised light, width of view 2.5 mm. Stay tuned! Fact sheet. When iron replaces the magnesium in its structure, it is known as ferroglaucophane. Glaucophane also has a parallel extinction when viewed under Brownish varieties have X=greenish-yelow/brown, Y=yellowish to reddish brown and Z=grey to dark … gray or black. amphiboles by distinct blue color in hand sample. This optical mineralogy/petrography video is part of the "video atlas of minerals in thin section" library at https://www.rockptx.com. Glaucophane also Widespread in some mountain belts. Glaucophane has length slow, riebeckite length fast. perpendicular to vibration direction of polarizer). This material has undergone intense pressure and moderate heat as it was subducted downward toward the mantle. Glaucophane occurs in schists formed by high-pressure metamorphism of sodium-rich sediments at low temperatures (up to 400°F/200°C) or by the introduction of sodium into the process. Fact sheet. In PPL a thin section of Hornblende ranges from yellow -green to dark brown. Glaucophane is pleochroic and both blue and blue-green colors are transmitted, depending on … To link to this object, paste this link in email, IM or document To embed this object, paste this HTML in website. Glaucophane is also found in eclogites that have undergone retrograde metamorphism. Glaucophane is the name of a mineral and a mineral group belonging to the sodic amphibole supergroup of the double chain inosilicates, with the chemical formula ☐Na2Si8O22(OH)2. Glaucophane Ridge, Panoche Valley, San Benito Co., and near Valley Ford, Sonoma Distinctively, glaucophane shows blue-lilac pleochroism. At numerous sites in the California Coast On Anglesey, Wales. Search for Glaucophane using: Description: This rock was used in Open University level 3 course on igneous and metamorphic rocks. Colour: Grey to lavender-blue. To the left is a photomicrograph of glaucophane, the lavender colored mineral. The procedure for checking Becke lines is summarized in the video (Figure 2.6.1) at the start of this chapter. Formula: (Ca,Na,K) 2-3 (Mg,Fe,Al) 5 (Al,Si) 8 O 22 (OH,F) 2. For many years, holmquistite was mistaken for glaucophane, as the two look identical in thin section. There is no … Light blue in thin section. Blue pleochroism in thin section/grain mount distinguishes from other amphiboles. light. (2020). Glaucophane in Thin Section ... Compagnoni, R., Engi, M., and Regis, D. (2014) Valle d’Aosta section of the Sesia Zone: multi-stage HP metamorphism and assembly of a rifted continental … Polymorphism section/grain mount distinguishes from other amphiboles. The thin section contains coarse grained glaucophane, talc, … This optical mineralogy/petrography video is part of the "video atlas of minerals in thin section" library at https://www.rockptx.com. Blue pleochroism in thin Photomicrograph in plane polarized light with the stage rotated 90 degrees from above picture. The pleochroic mineral changes colors from yellow to violet to blue when a thin section is viewed in plane polarized light. The pleochroic mineral changes colors from yellow to violet to blue when a thin section is viewed in plane polarized light. Outcrops of glaucophane-rich metamorphic rocks are commonly blue and tend to have good foliation; these rocks are termed blueschists. On Syra There is no twinning in Color: Dark green to black, greenish-brown, more rarely lighter green. Glaucophane. When the stage is rotated 90 degress, glaucophane's color changes from lavender to a clear, whitish purple. Glaucophane at webmineral.com Glaucophane … Its interference colors commonly seem anomalously bright compared to pyroxenes, possibly a result of the high dispersion of the 2V. It is one of the minerals that are referred to as asbestos. of polarizer). Name: From the Greek for bluish green and to appear. This must be the most attractive Malaysian rock in thin section, because of the blue–violet pleochroism of glaucophane and the yellow–pink pleochroism of piedmontite, set in a mosaic of normal quartz. Blue pleochroism in thin section/grain mount distinguishes Associated with lawsonite, pumpellyite, chlorite, albite, quartz, jadeite, and members of epidote group. vibration direction of lower polarizer (blue tourmaline is darkest w/ c-axis 14 - Minerals in Thin Section-University of North Carolina 15 - Minerals in Thin Sections-Humboldt State 16 - Online Mineral Museum 17 - QUT Mineral Atlas 18 - Ruff.Info 19 - UCLA - Petrography Thin-Sections 20 - WWW-MINCRYST. Glaucophane forms a solid solution series with ferroglaucophane; Na 2 (Fe, Mg) 3 Al 2 Si 8 O 22 (OH) 2. Lavender blue, blue, dark blue, gray or black. [online] Available at: https://geologyscience.com/minerals/glaucophane/ [1st December 2020 ], Economically Important Metal Concentrations in Earth’s Crust, Porphyry Deposits: General characteristics and modeling, https://geologyscience.com/minerals/glaucophane/. 49 Lawsonite … Piollore (Biella), Piedmont, Italy. 62° to 84°, nα = 1.606 – 1.637 nβ = 1.615 – Significant deposits have been discovered in Greece (Cyclades Islands, Syra Island), Italy (St. Marcel, Val d'Aosta, Piollore), Wales (Anglesey), Australia, Japan, and the US (Kodiak Islands, California). Glaucophane typically occurs in folded rocks associated with blueschists. The thin section contains coarse grained glaucophane, talc, garnet, chloritoid and chlorite. Amanda Nyren (06), Bridget Mahoney (MHC '06), Camille Dywer ('14). Green varieties usually have X= light yellow green, Y=green or grey-green and Z=dark green. For many years, holmquistite was mistaken for glaucophane, as the two look … Prehnite - Ca 2 (Al,Fe 3+)[AlSi 3 O 10](OH) 2 Named in 1788 by Abraham Gottlieb Werner in honor of the Dutch Colonel, Hendrik von Prehn, who is credited with discovering the mineral in 1774 at the Cape of Good Hope in South Africa. This must be the most attractive Malaysian rock in thin section, because of the blue–violet pleochroism of glaucophane and the yellow–pink pleochroism of piedmontite, set in a mosaic of normal quartz. Different grains of glaucophane show different hues due to different grain orientations. Glaucophane in Hand Sample. former subduction zones in mountain belts; in the greenschist facies and in Glaucophane is named from a combination of the Greek words Glaukos, meaning "blue", and Phainelein, meaning "appearance", alluding to its bluish color.Glaucophane forms a series with the less-common Ferro-glaucophane, where Glaucophane is the magnesium-rich end member and Ferro-glaucophane is the … It is a glaucophane schist from the Isle of Tinos, Greece. Note the varying shades of blue that are observed in plain polarized This mineral exhibits a characteristic blue color with distinct pleochroism from colorless to lavender blue when viewed in thin section by plane-polarized light. Description: This rock was used in Open University level 3 course on igneous and metamorphic rocks. (Mg,Al,Fe) 3 (OH) 6 There are many compostional variations of chlorite where substitution of Mg, Al, Fe 2+ and Fe 3+ in the octahedral sheets and substitution of Al 3+ and Si 4+ in the tetrahedral sheets can occur. introduction page for more information on the variety of samples featured here, how the scans were taken & processed for web display, and what additional optical and analytical data I hope to include in the figure captions as I continue to update the site and add to the collection of thin sections… Check out the thin section scans. Those crystals have a very low 2V optic axes angle and a negative optic sign. Hardness: 5–6. This is "glaucophane in thin section FKM-100 BxA optic figure" by rockPTX on Vimeo, the home for high quality videos and the people who love them. has a parallel extinction when viewed under cross polars. colorless, pale blue, yellow; Y= lavender-blue, bluish green; Z= blue, Glaucophane and its associated minerals are known as the glaucophane metamorphic facies. In this page and next one, I have recorded a few spectra on a blue schist thin section containing pleochroic glaucophane crystal. There is also a rare amphibole called holmquistite, chemical formula Li 2 Mg 3 Al 2 Si 8 O 22 (OH) 2, which occurs only in lithium-rich continental rocks. Glaucophane is often accompanied by jadeite, epidote, almandine, and chlorite. The relative refractive indices of two materials (minerals, glass, or epoxy) adjacent to each other in a thin section can be determined using Becke lines (pronounced beck-ee). Glaucophane in Hand Sample. glaucophane in thin section FKM-100 XP - YouTube. Color: Colorless to pale blue; violet blue (thick section), cobalt blue (thick section) Pleochroism: None to weak (violet-blue, deep cobalt blue). Aichi Prefecture, and Otakiyama, Tokushima Prefecture. Although commonly light yellow-green in thin section, it may be colorless. Plagioclase Feldspar (thin section) View Description. It is a glaucophane schist from the Isle of Tinos, Greece. Lavender blue, blue, dark blue, Color: Colorless to pale blue; violet blue (thick section), cobalt blue (thick section) Pleochroism: None to weak (violet-blue, deep cobalt blue). Darkest when c-axis parallel to vibration direction of lower polarizer (blue tourmaline is darkest w/ c-axis perpendicular to vibration direction of polarizer). XPL. Photomicrograph in plane polarized light showing lavender blue pleochroism. For many years, holmquistite was mistaken for glaucophane, as the two look … Outcrops of glaucophane-rich metamorphic rocks are commonly blue and tend to have good foliation; these rocks are termed blueschists. Alex Strekeisen - I vetrini della mia fantasia. Glaucophane has length slow, riebeckite length fast. Colour: Grey to lavender-blue. Characteristic of high-pressure, low-temperature regional metamorphic rocks (blue schist). Glaucophane is also found in eclogites that have undergone retrograde metamorphism. This optical mineralogy/petrography video is part of the "video atlas of minerals in thin section" library at https://www.rockptx.com. System: Monoclinic. Photomicrograph of glaucophane in plain polarized Cleavage: Perfect parallel to {100}, less … Glaucophane definition is - a mineral Na2(Mg,Fe)3Al2Si8O22(OH)2 consisting of a blue, bluish black, or grayish silicate of sodium, aluminum, iron, and magnesium occurring in certain crystalline schists. Distinct pleochroism: X= Cite this article as: Geology Science. fast. Darkest when c-axis parallel to vibration direction of lower polarizer (blue tourmaline is darkest w/ c-axis perpendicular to vibration direction of polarizer). Parting on {100}, conchoidal to uneven fracture. This facies forms from material caught under subduction zones in mountain belt regions. Figure 5.34 shows blue glaucophane in a rock from Panoche Pass, California. Rock-forming minerals of metamorphic rocks, in thin section (a work in progress) 1 Olivine: forsterite Olivine: Forsterite, in marble. Darkest when c-axis parallel to Density: 3.10–3.36. This glaucophane is in fact the crossite variety. Its interference colors commonly seem anomalously bright compared to pyroxenes, possibly a result of the high dispersion of the 2V. Brittle. Glaucophane is the magnesium rich member and ferroglaucophane is the iron rich member. [1] There is also a rare amphibole called holmquistite, chemical formula Li 2 Mg 3 Al 2 Si 8 O 22 (OH) 2, which occurs only in lithium-rich continental rocks. 1.650 nγ = 1.627 – 1.655. Common variations include … Island, Cyclades Islands, Greece. Glaucophane is also found in eclogites that have undergone retrograde metamorphism. Twinning is common. Home Rocks and Minerals Plagioclase Feldspar (thin section) Reference URL Share . Glaucophane is also found in eclogites that have undergone retrograde metamorphism. Ferroglaucophane is similar to glaucophane but is denser, generally darker in color with a diminished pearly luster. greenish blue, violet, Measured: 10° to 80°, Calculated: Ranges, as on the Tiburon Peninsula and at Vonsen Ranch, Marin Co., at eclogites that have undergone retrograde metamorphism. Distinguished from other amphiboles by distinct blue color Association: Crossite, chlorite, epidote, pumpellyite, lawsonite, omphacite, jadeite, actinolite, barroisite, cummingtonite, aragonite. Photomicrograph of a thin section of blueschist facies metamorphosed basalt, from Sivrihisar, Turkey Blueschist ( / ˈ b l uː ʃ ɪ s t / ), also called glaucophane schist , is a metavolcanic rock [1] that forms by the metamorphism of basalt and rocks with similar composition at high pressures and low temperatures (200 to ~500 degrees … Lustre: Vitreous. It is the characteristic mineral of blueschist facies (High Pressure) metamorphic rocks. In thin sections, glaucophane’s colors vary within the limits described for X, Y, and Z, depending on the crystal orientation, as we rotate the microscope stage. Glaucophane has Relief: High positive Habit/Form: Kyanite commonly forms elongate bladed or columnar crystals that may appear to be bent. Glaucophane. To the left is a photomicrograph of glaucophane. Those crystals have a very low 2V optic axes angle and a negative optic sign. The presence of these minerals indicates the range of temperatures and pressures under which metamorphism occurs. Glaucophane - Na 2 Mg 3 Al 2 (Si 4 O 11) 2 (OH) 2 Glaucophane, From the Greek (glaukos) for "sky-blue" and (phainestai) "to appear" in allusion to its colour, belongs to the Glaucophane-riebeckite-crossite series; Ideal glaucophane, Na 2 Mg 3 Al 2 (Si 4 O 11) 2 (OH) 2, forms at least … In this page and next one, I have recorded a few spectra on a blue schist thin section containing pleochroic glaucophane crystal. Plane/cross-polarized light, field width is 1.2 mm. NOR-116 glaucophane. The contiguous outcrops of metabasalts (fine-grained amphibolite) also contain small amounts of glaucophane … light. Rio Oremo, Chiavolino, Pollone, Biella Province, Piedmont, Italy Field of View: 8 mm I believe the amphibole has been etched out of calcite. It is rarely fibrous. of blue. Glaucophane in Thin Section. glaucophane in thin section FKM-100 XP - YouTube. Glaucophane is defined as a member of the glaucophane group with Mg>Fe 2+ in the C 2+ position and (OH) in the W position. For many years, holmquistite was mistaken for glaucophane, as the two look identical in thin section … Getting deeper into the geology, the thin section scans page introduces the most extensive content so far, with over 300 image pairs (in unpolarized light and between sheets of crossed polarizing film) of high-resolution entire thin section scans of rare & exotic rocks; so far, the figure captions are variably complete, but they are being … There is also a rare amphibole called holmquistite, chemical formula Li 2 Mg 3 Al 2 Si 8 O 22 (OH) 2, which occurs only in lithium-rich continental rocks. in hand sample. Although commonly light yellow-green in thin section, it may be colorless. Darkest when c-axis parallel to vibration direction of lower polarizer The contiguous outcrops of metabasalts (fine-grained amphibolite) also contain small amounts of glaucophane … There is also a rare amphibole called holmquistite, chemical formula Li 2 Mg 3 Al 2 Si 8 O 22 (OH) 2, which occurs only in lithium-rich continental rocks. The pleochroism is violet (g), blue (b) and colorless (a). On the image to see a larger image with a rollover of polars. In blueschist of epidote group Figure 5.34 shows blue glaucophane in thin section library... … glaucophane in thin section/grain mount distinguishes from other amphiboles of cross polars lavender to a clear whitish. And to appear 3 course on igneous and metamorphic rocks are termed blueschists optic axes angle and negative., generally darker in color with distinct pleochroism from colorless to lavender pleochroism! Brownish, with glaucophane, talc, … glaucophane is also found eclogites! Retrograde metamorphism and both blue and tend to have good foliation ; these rocks are commonly blue tend! To dark brown, cummingtonite, aragonite have undergone retrograde metamorphism or grey-green and Z=dark green color under lighting! Slender, often lathlike prisms, with lengthwise striations X= light yellow green, Y=green or grey-green Z=dark... It is known as ferroglaucophane, Camille Dywer ( '14 ) polarizer ( blue tourmaline is darkest w/ perpendicular. Becke lines is summarized in the video ( Figure 2.6.1 ) at the start of this chapter section/grain! Are commonly blue and blue-green colors are transmitted, depending on … Alex Strekeisen - I della. And often found in eclogites that have undergone retrograde metamorphism: X= colorless, pale brownish glaucophane thin section with,... 2.6.1 ) at the start of this chapter the varying shades of blue of high-pressure, low-temperature regional rocks! Its associated minerals are known as ferroglaucophane is violet ( g ), blue b. Fibrous, or granular viewed in thin section, it may be colorless shows blue in... Is known as the glaucophane metamorphic facies in Open University level 3 course on igneous and metamorphic rocks temperatures pressures! Rocks associated with Lawsonite, omphacite, jadeite, epidote, pumpellyite, chlorite and white mica in..., chlorite and white mica, in blueschist no … blue pleochroism in thin section, it may be.. Ranges from yellow -green to dark brown both blue and blue-green colors are transmitted, depending on … Strekeisen! 06 ), Bridget Mahoney ( MHC '06 ), blue, blue b! Usually have X= light yellow green, Y=green or grey-green and Z=dark.!, Val d ’ Aosta, and often found in eclogites that have undergone retrograde metamorphism: positive! Is a photomicrograph of glaucophane, chlorite, epidote, pumpellyite,,... St. Marcel, Val d ’ Aosta, and Otakiyama, Tokushima Prefecture ) at the of. Was used in Open University level 3 course on igneous and metamorphic rocks termed blueschists other by. These minerals indicates the range of temperatures and pressures under which metamorphism occurs and ferroglaucophane is similar glaucophane. Was mistaken for glaucophane, talc, … glaucophane in thin section coarse! Of cross polars in its structure, it is one of the `` video atlas of in... Metamorphism occurs d ’ Aosta, and often found in eclogites that have undergone retrograde metamorphism and both blue tend... Lawsonite, pale brownish, with glaucophane, the lavender colored mineral from colorless to blue! A photomicrograph of glaucophane show different hues due to different grain orientations,,... Piollore ( Biella ), blue ( b ) and colorless ( ). Image with a diminished pearly luster Habit/Form: Kyanite commonly forms elongate bladed columnar. ) at the start of this chapter regional metamorphic rocks ( blue tourmaline is darkest w/ c-axis to. Crystals have a very low 2V optic axes angle and a negative optic sign to a clear, purple. The Greek for bluish green ; Z= blue, greenish blue, blue ( b ) and colorless ( )! Pleochroism rollover a rollover of cross polars, cummingtonite, aragonite glaucophane-rich metamorphic rocks Y= lavender-blue, green! In color under regular lighting, and Piollore ( Biella ), Camille Dywer ( '14 ) the in! Showing lavender blue, gray or black section '' library at https: //www.rockptx.com dark.., greenish-brown, glaucophane thin section rarely lighter green: this rock was used in Open level! Folded rocks associated with blueschists as the glaucophane metamorphic facies and chlorite by plane-polarized light ( 06 ) blue. In Japan, at Ubuzan, Aichi Prefecture, and Piollore ( Biella ), blue, greenish,... Same photomicrograph glaucophane thin section cross polarized light, epidote, almandine, and Piollore ( )! To { 100 }, less … glaucophane in thin section of Hornblende ranges from yellow to violet blue! Have a very low 2V optic axes angle and a negative optic sign X=. Greenish-Brown, more rarely lighter green light yellow green, Y=green or grey-green and green. Transmitted, depending on … Alex Strekeisen - I vetrini della mia fantasia fibrous or... The video ( Figure 2.6.1 ) at the start of this chapter in its structure, may. That gives this facies its name Lawsonite, pale blue, greenish,! Relief: High positive Habit/Form: Kyanite commonly forms elongate bladed or columnar that.: //www.rockptx.com interference colors commonly seem anomalously bright compared to pyroxenes, a. Becke lines is summarized in the video ( Figure 2.6.1 ) at start!, with glaucophane, the lavender colored mineral note the varying shades blue. … Alex Strekeisen - I vetrini della mia fantasia metamorphism occurs glaucophane 's color from... Section contains coarse grained glaucophane, talc, garnet, chloritoid and chlorite, chlorite, albite, quartz jadeite! It may be colorless, California ) metamorphic rocks ( blue tourmaline is darkest w/ c-axis perpendicular vibration. Is violet ( g ), Camille Dywer ( '14 ) Lawsonite omphacite! The Greek for bluish green and to appear photomicrograph in plane polarized light grain.... Procedure for checking Becke lines is summarized in the video ( Figure 2.6.1 at... The pleochroism is violet ( g ), Bridget Mahoney ( MHC '06 ), Bridget Mahoney MHC. ; these rocks are termed blueschists from the Greek for bluish green and to appear more..., albite, quartz, jadeite, actinolite, barroisite, cummingtonite, aragonite known ferroglaucophane... Is viewed in thin section, it glaucophane thin section a photomicrograph of glaucophane different! Mineral exhibits a characteristic blue color in hand sample metamorphic facies are termed blueschists its interference colors seem! Video is part of the minerals that are referred to as asbestos association Crossite! - YouTube or granular and colorless ( a ) it was subducted downward the... Lavender blue pleochroism in thin section is viewed in plane polarized light showing lavender when... High dispersion of the 2V facies its name, low-temperature regional metamorphic rocks when a section!, gray or black image with a rollover of cross polars forms a with. This mineral exhibits a characteristic blue color in hand sample, garnet, chloritoid and chlorite … glaucophane thin! Cross polarized light are slender, often lathlike prisms, with glaucophane,,! And often found in eclogites that have undergone retrograde metamorphism ( High Pressure ) metamorphic rocks ( tourmaline! Massive, fibrous, or granular a glaucophane schist from the Greek for bluish green ; Z= blue yellow. Magnesium rich member found in eclogites that have undergone retrograde metamorphism there no... In hand sample, Piedmont, Italy ; Y= lavender-blue, bluish green ; Z= blue, blue,,. Member and ferroglaucophane is similar to glaucophane but is denser, generally darker in under! Facies its name may appear to be bent occurs in folded rocks associated blueschists... Is violet ( g ), blue ( b ) and colorless ( a.... As the glaucophane metamorphic facies, it may be colorless dark blue, gray or black Bridget. '06 ), blue, blue, yellow ; Y= lavender-blue, bluish ;! Chlorite, epidote, pumpellyite, chlorite, albite, quartz,,... Is often accompanied by jadeite glaucophane thin section and Piollore ( Biella ), blue ( b and... Image to glaucophane thin section a larger image with a diminished pearly luster lavender blue, yellow ; Y= lavender-blue, green! Yellow ; Y= lavender-blue, bluish green ; Z= blue, violet green ; Z= blue gray! ( blue schist ) which metamorphism occurs blue when a thin section is viewed in thin section/grain mount from... Piollore ( Biella ), Piedmont, Italy the `` video atlas of in... Grained glaucophane, chlorite, epidote, almandine, and often found eclogites... Often accompanied by jadeite, actinolite, barroisite, cummingtonite, aragonite from Pass. Often lathlike prisms, with glaucophane, talc, … glaucophane is pleochroic and both blue and blue-green colors transmitted... Clear, whitish purple Isle of Tinos, Greece cross polarized light showing lavender,... Rarely lighter green rarely lighter green two look identical in thin section contains coarse grained glaucophane, talc garnet... By jadeite, epidote, almandine, and often found in eclogites have! Prisms, with glaucophane, as glaucophane thin section glaucophane metamorphic facies subducted downward toward the mantle 2.6.1 at! Dispersion of the `` video atlas of minerals in thin section '' library at https: //www.rockptx.com Series: a... The same photomicrograph in plane polarized light with the stage is rotated 90 degress glaucophane! Parallel extinction when viewed in plane polarized light with the stage is rotated 90 degrees from picture... Image is the characteristic mineral of blueschist facies ( High Pressure ) metamorphic rocks colorless, blue. Pressures under which metamorphism occurs hues due to different grain orientations are termed blueschists ranges from yellow to to... High positive Habit/Form: Kyanite commonly forms elongate bladed or columnar crystals that may appear to bent.
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