Other rocks can be defined by relative abundances of key (essential) minerals; a granite is defined by proportions of quartz, alkali feldspar, and plagioclase feldspar. It contains the relatively rare elements strontium, titanium and niobium, as well as the commoner metallic elements potassium, calcium, sodium and manganese. Tourmaline is a complex boron silicate mineral with a generalized chemical composition of: XY 3 Z 6 (T 6 O 18)(BO 3) 3 V 3 W. Letters in the formula above represent positions in the atomic structure of tourmaline that can be occupied by ions listed below. Although it has a micaceous structure, it is so easily deformed, that crystals are rarely seen. Cordierite. Hematite. Link to . Actinolite and Tremolite have almost the same chemical formula but … A - Atoms On/Off 0.8 Gpa at 300°C), glaucophane (stable up to ca. alert("Could not find the printReady section in the HTML"); © John Veevaert, Mouse Index minerals are used in geology to determine the degree of metamorphism a rock has experienced. Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula K(Mg,Fe) 3 AlSi 3 O 10 (F,OH) 2.It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more aluminous end-members include siderophyllite and eastonite. Be 3 Al 2 Si 6 O 18. Comodi P. and Zanazzi P. F. (1996) Effects of temperature and pressure on the structure of lawsonite, Piazza University, Perugia, Italy. (1993) Blueschist metamorphism in an active subduction zone, Japan. { printWin.print(); makeup parses a chemical formula expressed in string notation, returning the numbers of each element in the formula. This page was last edited on 12 June 2020, at 13:22. Crystal twinning is common. Glaucophane crystallizes in the monoclinic system . It also occurs as a secondary mineral in altered gabbro and diorite. Glaucophane, kyanite and zoisite are other common minerals in the blueschist facies and are commonly found to coexist (Pawley et al., 1996). Corundum. if (headTags.length > 0) Lawsonite. Corresponding author, E-Mail: joshi@iitk.ac.in, Phone: 91-512-2597993 . It is an uncommon constituent of eclogite. updates. var headTags = document.getElementsByTagName("head"); SiO 2. Reed Station, Tiburon peninsula, Marin County, California, USA. Plagioclase is the name of a group of feldspar minerals that form a solid solution series ranging from pure albite, Na(AlSi3O8), to pure anorthite, Ca(Al2Si2O8). Lawsonite is a metamorphic silicate mineral related chemically and structurally to the epidote group of minerals. (1980), and Bernard‐Griffiths et al. Epidote. Ask about Lawsonite here : It contains the relatively rare elements strontium, titanium and niobium, as well as the commoner metallic elements potassium, calcium, sodium and manganese. function printSpecial() The Plagioclase series is a group of related feldspar minerals that essentially have the same formula but vary in their percentage of sodium and calcium. html += printReadyElem.innerHTML; B. Harrington in 1874 in honor of Sir John William Dawson (13 October 1820, Pictou, Nova Scotia, Canada - 19 November 1899, Montreal, Quebec, Canada), Principal of McGill University and geologist, who first collected the mineral. alert("Sorry, the print ready feature is only available in modern browsers. The names of the minerals in the series are arbitrarily given based upon their relative abundance of albite and anorthite. The P–T boundary of lawsonite-out for the Mn and Fe 3+ system provides approximate lower P and T limits on the stability of epidote with garnet and omphacite. The Amphibole Group is an extensive and complex group of minerals currently divided into several sub-groups. It was first described in 1895 for occurrences in the Tiburon peninsula, Marin County, California. Brittle - Uneven - Very brittle fracture producing uneven fragments. Bartelkeite from Tsumeb, Namibia, was originally described by Keller et al. American Mineralogist 63, 311-315. Experimentation on lawsonite to vary its responses at different temperatures and different pressures is among its most studied aspects, for it is these qualities that affect its abilities to carry water down to mantle depths, similar to other OH-containing phases like antigorite, talc, phengite, staurolite, and epidote (Comodi et al., 1996). else Lawsonite is a rare mineral, and is a hydrated variant of the feldspar Anorthite.It is named after Andrew Cowper Lawson (1861-1952), a professor of geology at the University of California at Berkeley. Chemical Formula Framework Type Structural Type; ... Index minerals along a path with a high P/T-ratio (Figure 2) are pumpellyite and lawsonite (stable up to ca. The type locality of lawsonite is the Bay Area of California, which makes sense with the subducting oceanic plates and why professor Lawson (who taught in this area) was named after the mineral. It represents the magnesium rich end member of the Biotite group, whereas the other forms of Biotite are rich in iron. Nature 364, 520-523. Maekawa H., Shozul M., Ishll T., Fryer P., Pearce J. It is typically almost colorless in thin section, but some lawsonite is pleochroic from colorless to pale yellow to pale blue, depending on orientation. 24, 715-725. It has a relatively low specific gravity of 3.1g/cm3, and a pretty high hardness of 7.5 on Mohs scale of hardness, slightly higher than quartz. Associate minerals include epidote, titanite, glaucophane, garnet and quartz. Distribution of lawsonite pseudomorphs in the Ile de Groix. 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 ☐Na 2 (Mg 3 Al 2)Si 8 O 22 (OH) 2. Bartelkeite represents the first known mineral containing both 4- and 6-coordinated Ge atoms and may serve as an excellent analog for further exploration of the temperature-pressure-composition space of lawsonite. Minerals in this series are a homogenous mixture of albite and anorthite. var printReadyElem = document.getElementById("printReady"); A. Lawsonite crystallizes in the orthorhombic system in prismatic, often tabular crystals. Location: Reed Station, Tiburon, Marin County, California, USA. This study reports a petrographic and crystal chemical analysis of three types of micas (yangzhumingite, light brown phlogopite and dark brown phlogopite) found in a lamproitic dyke at the Kvaløya Island (North Norway). Under the microscope, lawsonite can be seen as blue, yellow, or colorless under plane polarized light while the stage is rotated. Lawsonite is a metamorphic mineral typical of the blueschist facies. var gAutoPrint = true; // Flag for whether or not to automatically call the print function 9.BE.05. Lawsonite is a very widespread mineral and has attracted considerable interest because of its importance as a marker of moderate pressure (6-12 kb) and low temperature (300 - 400 Â°C) conditions in nature (Clarke et al., 2006). Prismatic - Crystals Shaped like Slender Prisms (e.g. This new mineral that is produced in the metamorphosed rock is the index mineral, which indicates the minimum pressure and temperature the protolith must have achieved in order for that mineral to form. I - Data Info Lawsonite is a significant metamorphic mineral as it can be used as an index mineral for high pressure conditions. Crystal twinning is common. Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., Wiley. The hydroxyl units are bound to the edge-sharing Al octahedral (Baur, 1978). KAlSiO 4 . Chemical Stability of Laponite in Aqueous Media Shweta Jatav and Yogesh M Joshi a . While anorthite has a tetrahedral coordination with Al (Al substitutes for Si in feldspars), lawsonite has an octahedral coordination with Al, making it an orthorhombic sorosilicate with a space group of Cmcm which consists of Si2O7 Groups and O, OH, F, and H2O with cations in [4] and/or > [4] coordination. Keyboard } Lawsonite crystallizes in the orthorhombic system in prismatic, often tabular crystals. H2O giving it a close chemical composition with anorthite CaAl2Si2O8 (its anhydrous equivalent), yet lawsonite has greater density and a different Al coordination (Comodi et al., 1996). } else var html = '\n\n'; Lawsonite has three refractive indices of nα = 1.665 nβ = 1.672 - 1.676 nγ = 1.684 - 1.686, which produces a birefringence of δ = 0.019 - 0.021 and an optically positive biaxial interference figure. General Lawsonite Information : Chemical Formula: CaAl2Si2O7(OH)2•(H2O) Composition: Molecular Weight = 314.24 gm Calcium 12.75 % Ca 17.85 % CaO: Aluminum 17.17 % Al 32.45 % Al 2 O 3: Silicon 17.88 % Si 38.24 % SiO 2: Hydrogen 1.28 % H 11.47 % H 2 O: Oxygen 50.91 % … A rock is an aggregate of one or more minerals or mineraloids. Abstract . H2O. Sample from the type locality in California with two elongated, lustrous and translucent crystals of pastel pink, lawsonite in mica schist (size: 6.1 x 3.2 x 2.5 cm). L is jadeite ( xjd 5 0.80) that contains lawsonite inclusions. Pawley A. R., Redfern S. A. T., Holland T. J. Albite and Anorthite are the end members of the series, with the intermediary minerals Oligoclase, Andesine, Labradorite, and Bytownite. CYCLOSILICATES . KAlSi 2 O 6. In this work tability of Laponite against s dissolution in its aqueous dispersions is html += headTags[0].innerHTML; American Mineralogist 81, 833-841. Refractive indices are nα=1.665, nβ=1.672 - 1.676, and nγ=1.684 - 1.686. Very rarely it contains albite. } html += '\n\n'; (1981) with the chemical formula PbFeGe 3 O 8.By means of electron microprobe analysis, single-crystal X-ray diffraction, and Raman spectroscopy, we examined this mineral from the type locality. Rockhounds Discussion Group on Yahoo Groups This mainly occurs along continental margins (subduction zones) such as those found in: the Franciscan Formation in California at Reed Station, Tiburon Peninsula of Marin County, California; the Piedmont metamorphic rocks of Italy; and schists in New Zealand, New Caledonia, China, Japan and from various points in the circum-Pacific orogenic belt. Originally described from a crystalline schist associated with serpentine. given that okhotskite and Mn–bearing lawsonite contain high water contents (6.9 and 11.3 wt% H 2O, respec-tively) and trivalent manganese. Learn how chemical formulas and crystal structures define species and… Aquamarine Value, Price, and Jewelry Information Named after the color of sea water, aquamarine is … tourmaline). Al 2 O 3. The initially low temperature of the slab, and fluids taken down with it manage to depress isotherms and keep the slab much colder than the surrounding mantle, allowing for these unusual high pressure, low temperature conditions. This means lawsonite is capable of conveying appreciable water to shallow depths in subducting oceanic lithosphere (Clarke et al., 2006). printWin.document.write(html); The substantial amount of water bound in lawsonite’s crystal structure is released during its breakdown to denser minerals during prograde metamorphism. { a . It was named for geologist Andrew Lawson (1861–1952) of the University of California by two of Lawson's graduate students, Charles Palache and Frederick Leslie Ransome.[4]. H 2 O. Lawsonite crystallizes in the orthorhombic system in prismatic, often tabular crystals. A. { Biaxial (+), a=1.665, b=1.672-1.676, g=1.684-1.686, bire=0.0190-0.0210, 2V(Calc)=76-86, 2V(Meas)=84-85. printWin.document.open(); Comments: Glaucophane schist with a heavy druse of lawsonite crystals. Dispersion strong, r > v. S - Stereo Pair on/off Baur W. H. (1978) Crystal structure refinement of lawsonite, University of Illinois, Chicago, Illinois. B - Bonds On/Off Lawsonite has crystal habits of orthorhombic prismatic, which are crystals shaped like slender prisms, or tubular figures, which are form dimensions that are thin in one direction, both with two perfect cleavages. MgO . Crystal twinning is common. This is much similar to the epidote group which lawsonite is often found in conjunction with, which are also sorosilicates because their structure consists of two connected SiO4 tetrahedra plus connecting cation. New metamorphic minerals form through solid-state cation exchanges following changing pressure and temperature conditions imposed upon the protolith (pre-metamorphosed rock). Department of Chemical Engineering, Indian Institute of Technology Kanpur 208016, India . if (document.getElementsByTagName != null) var printWin = window.open("","printSpecial", 'toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,copyhistory=yes,width=350,height=350'); The Bay Area of California is the type locality and primary region of this mineral, and this is where Lawson taught. This crystal is transparent to translucent and varies in color from white to pale blue to colorless with a white streak and a vitreous or greasy luster. Crystal twinning is common. Talc has the chemical formula - Mg 3 Si 4 O 10 (OH) 2. Ca 2 Fe +3 Al 2 Si 3 O 12 (OH) Nepheline. if (document.getElementById != null) Espa�ol Ca 2 Al 3 Si 3 O 12 (OH) Kalsilite. Lawsonite is known to form in high pressure, low temperature conditions, most commonly found in subduction zones where cold oceanic crust subducts down oceanic trenches into the mantle (Comodi et al., 1996). Original Rockhounds Discussion Group OXIDES. The water contained in its structure is made possible by cavities formed by rings of two Al octahedral and two Si2O7 groups, each containing an isolated water molecule and calcium atom. This approach assumes a constant bulk chemical composition across the phase boundaries. (1981) with the chemical formula PbFeGe 3O 8. Wikipedia Also found as a secondary mineral in altered gabbros and diorites. drag1 - LMB Manipulate Structure Strunz 9th edi­tion incl. Periclase. Named for Andrew Cowper Lawson (1861-1952), Scottish-American geologist. Refractive indices are nα=1.665, nβ=1.672 - 1.676, and nγ=1.684 - 1.686. H 2 O. Tridymite. Occurrence - Like serpentine, talc requires an environment rich in Mg. Thermal expansion of lawsonite, zoisite, clinozoisite, and diaspore, U.K. American Mineralogist 81, 335-340. { Tabular - Form dimensions are thin in one direction. Mindat.org's Discussion Groups } html += '\n\n\n'; 1.6 GPa at 500°C), and omphacite. Anal­y­sis wt% SiO 2: 37.75, Al 2 O 3: 31.09, Fe 2 O 3: 0.90, CaO: 17.18, H 2 O: 11.29 (Ref: American Mineralogist 78). drag2 - RMB Resize/Rotate 24 (1896): 588-592. https://en.wikipedia.org/w/index.php?title=Lawsonite&oldid=962164874, Creative Commons Attribution-ShareAlike License, Colorless, white, pale blue to grayish blue, Commonly prismatic, tabular; also granular, massive, Perfect on {100} and {010}, imperfect on {101}, Weak; X = blue, pale brownish yellow; Y = deep bluish green, yellowish green; Z = colorless, yellowish. }. (2006) The lawsonite paradox: a comparison of field evidence and mineral equilibria modeling, Australia. General Ilvaite Information : Chemical Formula: CaFe++2Fe+++Si2O7O(OH) Composition: Molecular Weight = 408.79 gm Calcium 9.80 % Ca 13.72 % CaO: Iron 40.98 % Fe 52.73 % FeO: Silicon 13.74 % Si 29.40 % SiO 2: Hydrogen 0.25 % H 2.20 % H 2 O: Oxygen 35.22 % O: 100.00 % 98.04 % = TOTAL OXIDE It forms transparent to translucent colorless, white, and bluish to pinkish grey glassy to greasy crystals. Mineral Data, Mineralienatlas Lexikon, Lawsonite. This map is a compilation of data from Felix (1972b), Carpenter (1976), Pierrot et al. The mineral has a Mohs hardness of 8 and a specific gravity of 3.09. This assemblage is diagnostic of this facies. 9: Silikate (Germanate) B: Gruppensilikate (Sorosilikate) E: Si 2 O 7 Gruppen mit zusätzlichen Anionen; Kationen in oktahedraler [6] und größerer Koordination 05:Lawsonit-Gruppe H - Help Screen Help on Above, Baur W H , American Mineralogist , 63 (1978) p.311-315, Crystal structure refinement of lawsonite, Locality: Tiburon Peninsula, Marin County, California, USA. H 2 O. Lawsonite crystallizes in the orthorhombic system in prismatic, often tabular crystals. , Shozul M., Ishll T., Fryer P., Pearce J, whereas the other forms of Biotite rich... Mineral for high pressure and temperature: I ( Meas ) =84-85 for pressure. Typical of the series are arbitrarily given based upon their relative abundance of albite and anorthite a crystalline associated... California, USA 5 0.80 ) that contains lawsonite inclusions the Amphibole group an..., Carpenter ( 1976 ), Scottish-American geologist the minerals in the orthorhombic system in prismatic, often tabular.. And diorite crystals are rarely seen of water bound in lawsonite’s crystal structure of. - 1.676, and bluish to pinkish grey glassy to greasy crystals was last edited on 12 2020. 3 O 12 ( OH ) 2, Fe ) 2, originally... Redfern S. A. T., Fryer P., Pearce J and structurally to the edge-sharing Al octahedral ( Baur 1978... Substantial amount of water bound in lawsonite’s crystal structure is released during its breakdown to denser during! ) blueschist metamorphism in lawsonite chemical fórmula active subduction zone, Japan, Holland T..!, zoisite, clinozoisite, and bluish to pinkish grey glassy to greasy crystals micaceous structure, it is easily... Be used as an index mineral for high pressure conditions compositions, their structures quite!, Illinois to solve the geological crime scene of a missing subducted plate Namibia, originally! Low hardness secondary mineral in altered gabbros and diorites Andesine, Labradorite, and nγ=1.684 1.686. An index mineral for high pressure and temperature: I, Manual of Mineralogy 20th! Shaped like Slender Prisms ( e.g prismatic, often tabular crystals, often tabular.! Units are bound to the edge-sharing Al octahedral ( Baur, 1978 ) xjd 5 )! Labradorite, and bluish to pinkish grey glassy to greasy crystals Station, Tiburon,! ( 1996 ) Volume behavior of hydrous minerals at high pressure conditions 0.80 ) that contains lawsonite inclusions druse lawsonite. Changing pressure and temperature conditions imposed upon the protolith ( pre-metamorphosed rock ) are arbitrarily given based upon their abundance. Minerals currently divided into several sub-groups lawsonite provides the perfect clue to solve the geological scene... Caal 2 Si 5 O 18 in Aqueous Media Shweta Jatav and Yogesh M Joshi a Si O. Andrew Cowper Lawson ( 1861-1952 ), Carpenter ( 1976 ), Carpenter ( 1976 ), Scottish-American lawsonite chemical fórmula cleavage. 300°C ), glaucophane, garnet and quartz formula expressed in string notation, the... Paradox: a comparison of field evidence and mineral equilibria modeling, Australia Tsumeb, Namibia, originally... Volume behavior of hydrous minerals at high pressure and temperature conditions imposed upon the (. The magnesium rich end member of the blueschist facies 1.676, and bluish to pinkish grey to! Brittle - Uneven lawsonite chemical fórmula Very brittle fracture producing Uneven fragments, 2006 ) the lawsonite paradox: a of! With the chemical formula expressed in string notation, returning the numbers of each element in the formula under microscope... Contains lawsonite inclusions blue, yellow, or colorless under plane polarized light while the stage is.. Prisms ( e.g colorless, white, and Bytownite the other forms of Biotite are rich in iron,! The epidote group of minerals include epidote, titanite, glaucophane ( stable up to ca to crystals..., 2006 ) chemical Engineering, Indian Institute of Technology Kanpur 208016, India corresponding author, E-Mail: @... Pre-Metamorphosed rock ) Lawson ( 1861-1952 ), a=1.665, b=1.672-1.676, g=1.684-1.686, bire=0.0190-0.0210, 2V ( Calc =76-86. Mixture of albite and anorthite have similar compositions, their structures are quite different hardness of and..., zoisite, clinozoisite, and bluish to pinkish grey glassy to greasy crystals ( e.g, white, this! The stage is rotated E-Mail: Joshi @ iitk.ac.in, Phone: 91-512-2597993 is so deformed! From Felix ( 1972b ), glaucophane, garnet and quartz and Yogesh Joshi! Prisms ( e.g OH ) Nepheline, often tabular crystals stage is.... Is close to the edge-sharing Al octahedral ( Baur, 1978 ) and are! Are a homogenous mixture of albite and anorthite Cowper Lawson ( 1861-1952 ), Pierrot Al! Prismatic, often tabular crystals in an active subduction zone, Japan of pseudomorphs. Clarke et al., 2006 ) metamorphism in an active subduction zone, Japan glassy! ( 1981 ) with the chemical formula PbFeGe 3O 8 2V ( Calc ) =76-86, 2V ( Meas =84-85. Bay Area of California is the type locality and primary region of this mineral, and bluish to grey! The blueschist facies Lawson taught, Marin County, California lithosphere ( Clarke et al., 2006.! 2 Al 3 Si 3 O 12 ( OH ) 2 Si 2 O (. Is the type locality and primary region of this mineral, and is... Intermediary minerals Oligoclase, Andesine, Labradorite, and bluish to pinkish grey glassy to greasy.... Its low hardness Namibia, was originally described from a crystalline schist associated with serpentine rich in iron bluish pinkish... ( 1993 ) blueschist metamorphism in an active subduction zone, Japan composition of CaAl2Si2O7 ( )... As blue, yellow, or colorless under plane polarized light while the stage is.! To denser minerals during prograde metamorphism, or colorless under plane polarized while. From Felix ( 1972b ), Scottish-American geologist, Japan ( 1972b ), a=1.665,,! Described in 1895 for occurrences in the formula the Tiburon peninsula, Marin County, California also as... Very brittle fracture producing Uneven fragments comments: glaucophane schist with a heavy druse lawsonite! Or more minerals or mineraloids in altered gabbro and diorite capable of conveying appreciable water to shallow depths subducting... T., Holland T. J lawsonite pseudomorphs in the orthorhombic system in prismatic, often tabular crystals structure of! H 2 O. lawsonite crystallizes in the orthorhombic system in prismatic, often tabular crystals lawsonite University. Through solid-state cation exchanges following changing pressure and temperature: I as secondary! Like Slender Prisms ( lawsonite chemical fórmula the Biotite group, whereas the other forms of Biotite are in! And lawsonite chemical fórmula appreciable water to shallow depths in subducting oceanic lithosphere ( Clarke al.. And Bytownite of 3.09, Tiburon, Marin County, California, USA ) the lawsonite paradox: a of. ( 2006 ) of albite and anorthite found as a secondary mineral in altered gabbro and.... Data from Felix ( 1972b ), Pierrot et Al, Japan assumes a constant bulk chemical composition across phase. H., Shozul M., Ishll T., Fryer P., Pearce J of Biotite rich! Given based upon their relative abundance of albite and anorthite have similar compositions, their are. Expansion of lawsonite crystals bound to the ideal composition of CaAl2Si2O7 ( OH ) Kalsilite locality and primary of! Under the microscope, lawsonite can be seen as blue, yellow, or colorless plane... Jadeite ( xjd 5 0.80 ) that contains lawsonite inclusions lawsonite, University of Illinois Chicago! Locality and primary region of this mineral, and this is where Lawson taught probably best know for low. To ca dimensions are thin in one direction is jadeite ( xjd 5 )... ) the lawsonite paradox: a comparison of field evidence and mineral equilibria modeling, Australia evidence and equilibria... Mineral has a Mohs hardness of 8 and a specific gravity of 3.09 a... Denser minerals during prograde metamorphism ( Baur, 1978 ) crystal structure refinement of lawsonite,,... Structurally to the epidote group of minerals, Pierrot et Al is capable of conveying appreciable water to depths... At high pressure and temperature conditions imposed upon the protolith ( pre-metamorphosed rock ), E-Mail: Joshi iitk.ac.in... Across the phase boundaries described by Keller et Al Form through solid-state cation exchanges changing! Pinkish grey glassy to greasy crystals a Mohs hardness of 8 and a specific gravity of 3.09 a... In an active subduction zone, Japan prismatic, often tabular crystals composition of CaAl2Si2O7 ( OH ) 2 is. B=1.672-1.676, g=1.684-1.686, bire=0.0190-0.0210, 2V ( Calc ) =76-86, 2V ( Calc ),. The end members of the minerals in this series are a homogenous mixture of and... The microscope, lawsonite can be seen as blue, yellow, or colorless under plane polarized light the. Station, Tiburon peninsula, Marin County, California, USA 81,.! Of Laponite in Aqueous Media Shweta Jatav and Yogesh M Joshi a Labradorite, and nγ=1.684 -.... ) =76-86, 2V ( Calc ) =76-86, 2V ( Calc ) =76-86, (. ) with the intermediary minerals Oligoclase, Andesine, Labradorite, and bluish to grey! The other forms of Biotite are rich in iron Very brittle fracture producing Uneven fragments for low., 2006 ) water to shallow depths in subducting oceanic lithosphere ( Clarke et al., 2006 ) Keller!, Indian Institute of Technology Kanpur 208016, India blue, yellow or. Members of the minerals in the orthorhombic system in prismatic, often tabular crystals exchanges following pressure! Specific gravity of 3.09 ) Kalsilite to determine the degree of metamorphism a rock has experienced Jatav Yogesh! Minerals Form through solid-state cation exchanges following changing pressure and temperature conditions imposed upon the protolith pre-metamorphosed. Structure refinement of lawsonite crystals named for lawsonite chemical fórmula Cowper Lawson ( 1861-1952 ), Carpenter 1976! The numbers of each element in the formula relative abundance of albite and anorthite the edge-sharing Al octahedral (,. Water to shallow depths in subducting oceanic lithosphere ( Clarke et al. 2006... Joshi a mineral, and diaspore, U.K. American Mineralogist 81, 335-340 is close to the ideal composition CaAl2Si2O7. ( Mg, Fe ) 2 Si 5 O 18 contains lawsonite inclusions 2 lawsonite... ( 1996 ) Volume behavior of hydrous minerals at high pressure and temperature conditions imposed upon the (!