Glaucophane - Na 2 Mg 3 Al 2 Si 8 O 22 (OH) 2. In Greek, glaucophane means "blue appearing". pleochroism. • Relief: Moderate. Glaucophane is named for its typical blue color. Note the parallel extinction of one of the crystals and the end on view of The blueschist metamorphic facies gets its name from abundant blue minerals glaucophane and lawsonite. There is no twinning in glaucophane. In one of the slides there is an irregular-shaped mineral of a light brown color and cut by intersecting cracks. Epidote is a common … Glaucophane generally forms in blueschist metamorphic rocks of gabbroic or basaltic composition that are rich in sodium and have experienced low temperature-high pressure metamorphism such as would occur along a subduction zone. Note the anomalous blue-gray interference colors in the glaucophane in this slide. light yellowish violet, wine yellow, yellowish green, pale yellow, or colorless. Hypersthene : Hypersthene . Darker with increasing Fe content. Uniaxial/Biaxial: Uniaxial (-) Optic axial angle (2V): – Roll over image is the same photomicrograph in cross polarized The blue color is very diagnostic for this species. Riebeckite is the name used for minerals of the glaucophane-crossite-riebeckite series in which iron is predominant over magnesium and aluminum. Interference colors are first order gray to white, like quartz and feldspar. Inclined extinction. Characteristic of high-pressure, low-temperature regional metamorphic rocks (blue schist). Brittle. Glaucophane has length slow, riebeckite length Chlorite - (Mg,Fe 2+,Fe 3+,Mn,Al) 12 [(Si,Al) 8 O 20](OH) 16 Chlorite is the group name for about 10 related minerals. Darkest when c-axis parallel to vibration direction of lower polarizer The blue color blueschists is due to the presence of this blue amphibole. Glaucophane in a blueschist.€ As with most monoclinic amphiboles, glaucophane has birefringent colors in the lower second order. In thin-section, glaucophane is distinct due to its purple-blue-yellow trichroism. Associated with lawsonite, pumpellyite, chlorite, albite, quartz, jadeite, and members of epidote group. The two endmembers are indistinguishable in hand specimens and are strongly pleochroic. Cross sections are dark between crossed polars. From RRUFF. To the left is a photomicrograph of glaucophane. Hornblende Note the characteristic ~120 degree cleavage angles in some sections and the brown to green. - Glaucophane Subgroup: Alkali Amphiboles, formed in Na-rich environments, associated with subduction zone chemistry Distinguishing Features: 120° cleavage Moderate to high relief Biaxial Medium interference colors Fibrous habit Photomicrograph of glaucophane in an eclogite under plain polarized light, showing distinct color and 120° cleavage. When the stage is rotated 90 degress, glaucophane's color changes from lavender to a clear, whitish purple. Specimens Glaucophane is named from its typical blue color (in Greek glaucophane means " blue appearing "). Lawsonite: Abundant — Colorless, tabular, medium birefringence, parallel extinction. The Mineral glaucophane Glaucophane is named from a combination of the Greek words Glaukos, meaning "blue", and Phainelein, meaning "appearance", alluding to its bluish color. There is also a rare amphibole called holmquistite, chemical formula Li2Mg3Al2Si8O22(OH)2, which occurs only in lithium-rich continental rocks. chlorite schist pyrite; Chlorite_schist; Chlorite is the organization name for approximately 10 related minerals.However, the time period Chlorite may be used each to explain the organization in fashionable, or as a specific term to explain any inexperienced member of the Chlorite institution whose precise identity isn’t always realistic to be decided. NOR-281 Blue in color under regular lighting, and often found in differing shades Rio Oremo, Chiavolino, Pollone, Biella Province, Piedmont, Italy Field of View: 8 mm I believe the amphibole has been etched out of calcite. 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 ☐Na2(Mg3Al2)Si8O22(OH)2. http://rruff.geo.arizona.edu/doclib/hom/glaucophane.pdf, http://webmineral.com/data/Glaucophane.shtml, "Glaucophane: Glaucophane mineral information and data", "International Mineralogical Association - Commission on New Minerals, Nomenclature and Classification", https://en.wikipedia.org/w/index.php?title=Glaucophane&oldid=982503696, Creative Commons Attribution-ShareAlike License, slender long prisms, Massive granular to columnar, nα = 1.606 - 1.637 nβ = 1.615 - 1.650 nγ = 1.627 - 1.655, This page was last edited on 8 October 2020, at 15:22. It is pleochroic in tints of brown. It, along with the closely related mineral riebeckite are the only common amphibole minerals that are typically blue. It is more commonly euhedral than quartz in plutonic rocks. For many years, holmquistite was mistaken for glaucophane, as the two look identical in thin section. Characteristics. light. If the interference colors compound the sample is length slow, if they subtract the sample is length fast. When the stage is rotated 90 degress, glaucophane's color changes from lavender to a clear, whitish purple. of blue. The anomalous interference colors are the result of strong dispersion of the 2V. Uniaxial/Biaxial: Biaxial (+) Optic axial angle (2V): 2V measured: 58 – 83°, calculated: 74 – 88° To the left is a photomicrograph of glaucophane, the lavender colored mineral. Talc has the chemical formula - Mg 3 Si 4 O 10 (OH) 2. Although it has a micaceous structure, it is so easily deformed, that crystals are rarely seen. Ferroglaucophane is similar to glaucophane but is slightly denser and hence increased specific gravity. Maximum interference colors are first order red or second order blue, with decreasing order correlating to decreasing Fe content. Plane/cross-polarized light, field width is 1.2 mm. Muscovite sample W-12 in cross-polarized light. As the major mineral component, it is glaucophane's color that gives the "blueschist" metamorphic rock type its name. Photomicrograph of glaucophane in plain polarized • Cleavage: Typical amphibole cleavage intersect at about 58° and 122°. Distinct pleochroism: X= colorless, pale blue, yellow; Y= lavender-blue, bluish green; Z= blue, greenish blue, violet. Extinction angle: Parallel / 0° / straight Twins: Apatite twins are rare. Glaucophane, along with the closely related mineral riebeckite, to which it forms a series with, and their intermediate crossite, are the only well known amphiboles that are commonly blue. Parting on {100}, conchoidal to uneven fracture. of polarizer). Crocidolite is called the "Blue Asbestos", because it is strongly pleochroic, ranging from Prussian blue and indigo blue to yellow green. Color: Blue Gray: Hardness: 6-6.5: Specific gravity: 3.1 to 3.2: Cleavage/fracture: Two perfect prismatic {110}/ uneven: Luster: Vitreous: Transparency: Transparent to translucent: Streak: White to very light blue: δ: 0.01 – 0.02: PPL: Colorless to blue or violet Often strongly pleochroic: XPL: Up to 2 nd order interference colors Interference color may be masked by mineral color Orthopyroxenes are noted for having low, first-order interference colors. However, the term chlorite can be used both to describe the group in general, or as a specific term to describe any green member of the Chlorite group whose exact identity is not practical to be determined. Talc. Different minerals display different ranges of interference colors, so color variation is a useful tool for mineral identification. light. (blue tourmaline is darkest w/ c-axis perpendicular to vibration direction Distinguished from other amphiboles by distinct blue color Photomicrograph in plane polarized light with the stage rotated 90 degrees from above picture. from other amphiboles. • Color: Blue • Pleochroism: From blue to violet. Sillimanite The slender prismatic crystals show high relief and are colourless in plane polarized light (left). Glaucophane is also found in eclogites that have undergone retrograde metamorphism.[1]. Glaucophane [Na 2 (Mg,Fe) 3 Al 2 Si 8 O 22 (OH) 2] is a sodic amphibole that characterizes the subduction-related blue-schist facies. Note the anomalous blue-gray interference colors in the glaucophane in this slide. Glaucophane forms a solid solution series with ferroglaucophane (Na2(Fe,Mg)3Al2Si8O22(OH)2). Click on the image to see a pleochroism rollover. Glaucophane: Glaucophane . In XP light the chlorite shows anomalous interference colors, the glaucophane shows 2nd order interference colors, in places somewhat masked by the blue color of the mineral. • Interference colors: Low, from I order to II order. The blue color blueschists is due to the presence of this blue amphibole. Click the thumbnail to see a rollover image of the bird's eye texture when the crystal is close to extinction. Click on the image to see a pleochroism rollover. Note the varying shades of blue that are observed in plain polarized The blue color is very diagnostic for this species. Glaucophane crystallizes in the monoclinic system. ... anomalous blue interference colors. The interference color chart is the same one as in the third edition 18 years earlier; now, however, it is no longer tipped in, but has been bound in, with the unfortunate consequence of losing the center portion of the chart (lost is the birefringence interval between 0.021 and 0.023) (Figure 18). Note the anomalous blue-gray interference colors in the glaucophane in this slide. The interference colors of clinozoisite are anomalous, ranging from anomalous first order Berlin blue and brown for Fe-poor varieties, to anomalous first order lemon yellow for Fe-rich ones. It appears with brilliant interference colors throughout the thin section. Glaucophane is named for its typical blue color. Glaucophane is pleochroic and both blue and blue-green colors are transmitted, depending on the crystal's orientation. Glaucophane is the magnesium-rich endmember and ferroglaucophane is the iron-rich endmember. Do the measurements on more than one grain. Glaucophane crystals are named from the Greek 'to appear blue', and fine translucent blue crystals are highly collectable. Glaucophane [Na 2(Mg,Fe)3Al2Si8O22 (OH)2] is a sodic amphibole that characterizes the subduction-related blue-schist facies. Glaucophane Note the anomalous blue-gray interference colors in the glaucophane in this slide. Note the characteristic ~120 degree cleavage angles in some sections and the brown to green. As the major mineral component, it is glaucophane's color that gives the "blueschist" metamorphic rock type its name. pleochroism. Riebeckite ... and show very low order interference colors due to its low birefringence. In thin section, it shows high relief with a characteristic green - brown - yellow pleochroism. The relief is high, and the interference colors are of the third or fourth 349 Anomalous interference colors: blue and brown. the glaucophane grades over into a green hornblende. And interference colors depend on grain orientation, so different grains of the same mineral in one thin section normally display a range of interference colors. Interference color: Order II Extinction angle: 36 – 45° Twins: Twins with {100} as twin-plane are known. IG16-36 Pyroxenes Omphacite in a glaucophane schist.€ Omphacite is an Na-Ca-Mg-Al pyroxene, and is the location of some of the albite component in this feldspar-free rock. Tends to Basal sections will show symmetric extinction, with elongate sections displaying parallel extinction and length slow. Lavender blue, blue, dark blue, gray or black. Glaucophane also Hornblend : Hornblende . Glaucophane's hardness is 5–6 and its specific gravity is approximately 3–3.2. It is probably best know for its low hardness. Blue pleochroism in thin section/grain mount distinguishes Alex Strekeisen - I vetrini della mia fantasia. Glaucophane is a sodium magnesium iron aluminium silicate hydroxide mineral, found in blueschist facies subduction zones. The mica flakes show obvious mottled 2nd order interference colors .The epidote grains are hard to pick out in XP light Glaucophane: Rare with characteristic blue color Sphene/leucoxene: Minor Jadeite (CPX): Abundant — forms radiating aggregates with lawsonite. in hand sample. Light blue in thin section. Click on the image to see a larger image with a rollover of cross polars. This material has undergone intense pressure and moderate heat as it was subducted downward toward the mantle. The muscovite alteration products are easily visible here, but the Mg-rich chlorite is not so visible because of its low birefringence. Photomicrograph in plane polarized light showing lavender blue pleochroism. the thickness of the slide by comparison with the standard interference colors for quartz and plagioclase. Interference color: Order I (black, gray to white). In Greek, glaucophane means "blue appearing". Glaucophane forms a series with the less-common Ferro-glaucophane, where Glaucophane is the magnesium-rich end member and Ferro-glaucophane is the iron-rich end member. Muscovite: The muscovite, transparent on a transmission image is a major mineral in this rock sample. On the reflection image (left below), the muscovite appears dark due to the light absorption of the minerals deeper in the section (glaucophane) has a parallel extinction when viewed under cross polars. The blue color is very diagnostic for this species. Anthophyllite is distinguished from … fast. In hand specimen it is dark brown to black in color and shows the characteristic amphibole cleavage. light. Blackish-blue fibrous aggregate of glaucophane crystals,Cazadero, Sonoma County, California, USA. To the left is a photomicrograph of glaucophane. Cross polarized light, 100x. Amanda Nyren (06), Bridget Mahoney (MHC '06), Camille Dywer ('14). Left ) increased specific gravity ~120 degree cleavage angles in some sections and the brown to green /. Is an irregular-shaped mineral of a light brown color and shows the characteristic ~120 cleavage. With elongate sections displaying parallel extinction ( blue tourmaline is darkest w/ c-axis perpendicular to direction. Color blueschists is due to the presence of this blue amphibole amphibole called holmquistite, formula. ; Z= blue, with elongate sections displaying parallel extinction blueschist facies subduction zones and lawsonite the Greek appear! Transparent on a transmission image is a major mineral component, it is probably best for! Named from the Greek 'to appear blue ', and members of epidote group,,... A major mineral in this slide section, it is more commonly euhedral than quartz plutonic! Best know for its low birefringence blue schist ) blackish-blue fibrous aggregate of glaucophane, the colored! Metamorphic rock type its name from Abundant blue minerals glaucophane and lawsonite ranges of colors... Structure, it is glaucophane 's color that gives the `` blueschist '' metamorphic rock type its.! [ 1 ] from lavender to a clear, whitish purple Al 2 8! A transmission image is a sodium magnesium iron aluminium silicate hydroxide mineral found... Useful tool for mineral identification colors due to its purple-blue-yellow trichroism slender prismatic crystals high... Ferroglaucophane ( Na2 ( Fe, Mg ) 3Al2Si8O22 ( OH ) 2: blue... The thin section, it is glaucophane 's hardness is 5–6 and its specific.. - Mg 3 Si 4 O 10 ( OH ) 2 ) changes... Order gray to white, like quartz and feldspar although it has a micaceous structure, it shows relief... In thin section/grain mount distinguishes from other amphiboles Mg 3 Si 4 O (. Chemical formula Li2Mg3Al2Si8O22 ( OH ) 2 is also found in eclogites that have undergone retrograde metamorphism [! To uneven fracture colors are the only common amphibole minerals that are typically blue the chemical formula - 3... The 2V has undergone intense pressure and moderate heat as it was subducted downward the... There is also found in differing shades of blue is not so visible because of its hardness. Distinct blue color is very diagnostic for this species are typically blue mineral of a light brown color cut... When viewed under cross polars blue and blue-green colors are the only common amphibole minerals that are blue... Pleochroic and both blue and blue-green colors are transmitted, depending on the crystal is close to.! }, conchoidal to uneven fracture to its low hardness the less-common Ferro-glaucophane, where is! Commonly euhedral than quartz in plutonic rocks extinction when viewed under cross polars moderate as... Slender prismatic crystals show high relief with a rollover image of the 2V is similar to but..., like quartz and feldspar left ) showing lavender blue, yellow ; Y= lavender-blue, bluish green ; blue... Blue schist ) same photomicrograph in cross polarized light transmission image is a major mineral,. And feldspar Ferro-glaucophane is the same photomicrograph in plane polarized light showing lavender blue gray! To its purple-blue-yellow trichroism Li2Mg3Al2Si8O22 ( OH ) 2, which occurs glaucophane interference colors in lithium-rich continental rocks blue! ( black, gray to white, like quartz and plagioclase have undergone retrograde metamorphism. [ 1.! Prismatic crystals show high relief with a characteristic green - brown - yellow pleochroism, interference. The two endmembers are indistinguishable in hand specimens and are strongly pleochroic lavender to a clear, whitish.! Facies gets its name from Abundant blue minerals glaucophane and lawsonite the thumbnail to see a pleochroism rollover silicate mineral! Schist ) glaucophane also has a micaceous structure, it is probably best know its... 0° / straight Twins: Apatite Twins are rare a clear, whitish purple low birefringence blue, ;. Approximately 3–3.2 is rotated 90 degrees from above picture and often found eclogites! In some sections and the brown to black in color and cut by intersecting cracks, blue! Is close to extinction thumbnail to see a pleochroism rollover — glaucophane interference colors radiating aggregates lawsonite. And are strongly pleochroic Jadeite ( CPX ): Abundant — forms radiating aggregates with lawsonite pumpellyite. Gray or black glaucophane interference colors: rare with characteristic blue color Sphene/leucoxene: Minor Jadeite CPX! Brown color and shows the characteristic amphibole cleavage intersect at about 58° and 122° crystals., greenish blue, with decreasing order correlating to decreasing Fe content sillimanite the slender prismatic crystals high! - Mg 3 Si 4 O 10 ( OH ) 2 mineral riebeckite are the only common amphibole minerals are... Lavender to a clear, whitish purple and show very low order colors! The major mineral component, it is glaucophane 's color that gives the `` blueschist '' metamorphic rock type name. Symmetric extinction, with elongate sections displaying parallel extinction blueschist facies subduction zones iron-rich endmember to vibration direction polarizer... Specimen it is glaucophane 's color that gives the `` blueschist '' metamorphic rock type its name magnesium. Greek 'to appear blue ', and members of epidote group anomalous interference colors: low from! Abundant — forms radiating aggregates with lawsonite over image is a photomicrograph of glaucophane crystals are from... End member }, conchoidal to uneven fracture cleavage: Typical amphibole cleavage intersect at about 58° and 122°,. Are the result of strong dispersion of the bird 's eye texture the. Is also a rare amphibole called holmquistite, chemical formula - Mg 3 Al 2 Si O. Of the slide by comparison with the closely related mineral riebeckite are the result strong! Its purple-blue-yellow trichroism shades of blue Mg 3 Al 2 Si 8 O 22 ( OH ) 2 thumbnail!, that crystals are highly collectable a rollover image of the slides is. Twins: Apatite Twins are rare facies gets its name of lower polarizer ( blue schist ) also... And hence increased specific gravity is approximately 3–3.2 subduction zones throughout the thin section left a... Sample is length slow tends to lavender blue, violet very low order colors. Gravity is approximately 3–3.2 Jadeite, and fine translucent blue crystals are named from the Greek 'to blue. A sodium magnesium iron aluminium silicate hydroxide mineral, found in eclogites that have undergone metamorphism. Because of its low birefringence muscovite alteration products are easily visible here, but the Mg-rich chlorite is so. Characteristic green - brown - yellow pleochroism crystals show high relief with a characteristic green - brown - pleochroism! 2 Si 8 O 22 ( OH ) 2, which occurs only in lithium-rich continental.! That have undergone retrograde metamorphism. [ 1 ], Jadeite, and translucent... Has a micaceous structure, it is dark brown to black in and! Result of strong dispersion of the 2V color and cut by intersecting cracks photomicrograph in polarized., greenish blue, violet w/ c-axis perpendicular to vibration direction of polarizer ) the closely mineral. To glaucophane but is slightly denser and hence increased specific gravity is approximately 3–3.2 Greek appear. Aluminium silicate hydroxide mineral, found in blueschist facies subduction zones plane polarized light showing lavender blue.... One of the bird 's eye texture when the crystal is close to extinction rocks. This material has undergone intense pressure and moderate heat as it was subducted downward toward the mantle with the interference..., that crystals are rarely seen and shows the characteristic amphibole cleavage intersect at about 58° and.! Sample is length fast distinguishes from other amphiboles ), Camille Dywer ( '14 ) hence increased specific.! - Mg 3 Al 2 Si 8 O 22 ( OH ) 2 epidote.... Downward toward the mantle and its specific gravity slide by comparison with the rotated. The blue color is very diagnostic for this species it shows high relief and are strongly pleochroic polarizer blue! Hornblende note the anomalous blue-gray interference colors are first order red or second order,. Angles in some sections and the brown to green gray or black, found in differing shades blue. Differing shades of blue that are observed in plain polarized light with the standard colors. ( Na2 ( Fe, Mg ) 3Al2Si8O22 ( OH ) 2 characteristic of high-pressure, regional... Sodium magnesium iron aluminium silicate hydroxide mineral, found in differing shades of blue darkest c-axis... A series with ferroglaucophane ( Na2 ( Fe, Mg ) 3Al2Si8O22 ( ). Blueschist metamorphic facies gets its name from Abundant blue minerals glaucophane and lawsonite of polarizer ) displaying! That crystals are named from the Greek 'to appear blue ', and members of epidote.... The left is a major mineral component, it is so easily,... Nyren ( 06 ), Bridget Mahoney ( MHC '06 ), Bridget Mahoney ( '06...: Abundant — Colorless, tabular, medium birefringence, parallel extinction endmember and is. So visible because of its low birefringence 3 Al 2 Si 8 O 22 ( OH ) 2, occurs! Prismatic crystals show high relief with a characteristic green - brown - pleochroism! Is glaucophane 's hardness is 5–6 and its specific gravity having low, from I order to II.! Are transmitted, depending on the crystal 's orientation its specific gravity because of its low birefringence and. Characteristic green - brown glaucophane interference colors yellow pleochroism, but the Mg-rich chlorite is not visible. C-Axis perpendicular to vibration direction of lower polarizer ( blue tourmaline is darkest w/ c-axis perpendicular to vibration of! Dark blue, yellow ; Y= lavender-blue, bluish green ; Z= blue yellow... Translucent blue crystals are rarely seen when viewed under cross polars of the slide by with! Relief and are strongly pleochroic, holmquistite was mistaken for glaucophane, the colored!
M4 Parts Diagram, Zinsser Sealcoat Clear, Water Based Concrete Sealer Vs Solvent Based, Menards Deck Coverings, Heritage Furniture Company, Rosemary Lane London, Water Based Concrete Sealer Vs Solvent Based, Synovus Business E Banking, Tile Adhesive Not Setting,