Wollastonite

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Wollastonite
WollastoniteUSGOV.jpg
General
Category Inosilicate mineral
Formula
(repeating unit)		Calcium metasilicate, CaSiO3
IMA symbol Wo [1]
Strunz classification 9.DG.05
Crystal system Triclinic
Monoclinic polytype exists
Crystal class Pinacoidal (1)
(same H-M symbol)
Space group P1 (Triclinic)
P21/a (Monoclinic)
Unit cell a = 7.925  Å, b = 7.32 Å,
c = 7.065 Å; α = 90.055°,
β = 95.217°, γ = 103.42°; Z = 6
Identification
Formula mass 116.159 g/mol
ColorWhite, colorless or gray
Crystal habit Rare as tabular crystals—commonly massive in lamellar, radiating, compact and fibrous aggregates.
Twinning Common
Cleavage Perfect in two directions at near 90°
Fracture Splintery to uneven
Mohs scale hardness4.5 to 5.0
Luster Vitreous or dull to pearly on cleavage surfaces
Streak White
Diaphaneity Transparent to translucent
Specific gravity 2.86–3.09
Optical propertiesBiaxial (−)
Refractive index nα = 1.616–1.640
nβ = 1.628–1.650
nγ = 1.631–1.653
Birefringence δ = 0.015 max
2V angle Measured: 36° to 60°
Melting point 1540 °C
Solubility Soluble in HCl, insoluble in water
Other characteristicsHeat of formation (@298): −89.61kJ
Gibbs free energy: 41.78kJ
References [2] [3] [4] [5] [6]

Wollastonite is a calcium inosilicate mineral (Ca Si O 3) that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolomite is subjected to high temperature and pressure, which sometimes occurs in the presence of silica-bearing fluids as in skarns [7] or in contact with metamorphic rocks. Associated minerals include garnets, vesuvianite, diopside, tremolite, epidote, plagioclase feldspar, pyroxene and calcite. It is named after the English chemist and mineralogist William Hyde Wollaston (1766–1828).

Contents

Despite its chemical similarity to the compositional spectrum of the pyroxene group of minerals—where magnesium (Mg) and iron (Fe) substitution for calcium ends with diopside and hedenbergite respectively—it is structurally very different, with a third SiO4−4 tetrahedron [8] in the linked chain (as opposed to two in the pyroxenes).

Wollastonite output in 2005 2005wollastonite.PNG
Wollastonite output in 2005

Estimated world production of crude wollastonite ore was 1,200,000 tonnes in 2021. World reserves of wollastonite are estimated to exceed 100 million tonnes, though some existing deposits have not been surveyed.

Major producers of wollastonite include China, India, the United States, Mexico, and Finland. [9]

In the United States, wollastonite is mined in Willsboro, New York (the first laboratory for local wollastonite research was in Essex, New York by Koert Burnham in the 1940s. The original laboratory building still exists as a residential & commercial building) and Gouverneur, New York. Deposits have also been mined commercially in North Western Mexico. [10]

The price of raw wollastonite in 2008 varied between US$80 and US$500 per tonne depending on the country and size and shape of the powder particles. [10]

Uses

Wollastonite is among the fastest reacting silicates, but may have high costs associated with carbon storage. [11] Addition of wollastonite to soil stimulates organic carbon mineralization. [12]

Ceramics

Wollastonite has industrial importance in ceramics manufacturing as an additive. [13]

In ceramics, wollastonite decreases shrinkage and gas evolution during firing, increases green and fired strength, maintains brightness during firing, permits fast firing, and reduces crazing, cracking, and glaze defects.[ citation needed ]

Construction

Wollastonite can serve as a substitute for asbestos in floor tiles, friction products, insulating board and panels, paint, plastics, and roofing products. Similar to asbestos, wollastonite is resistant to chemical attack, stable at high temperatures, and improves flexural and tensile strength in composites. [10] In some industries, wollastonite is used in different percentages of impurities, such as its use as a fabricator of mineral wool insulation, or as an ornamental building material. [14] Wollastonite is used in a cement announced in 2019 which "reduces the overall carbon footprint in precast concrete by 70%." [15]

Wollastonite has been studied for carbon mineralization for storage of carbon dioxide (CO2) according to the following reaction: [16]

CaSiO3 + CO2 → CaCO3 + SiO2

Metallurgy

In metallurgical applications, wollastonite serves as a flux for welding, a source for calcium oxide, a slag conditioner, and to protect the surface of molten metal during the continuous casting of steel.[ citation needed ]

Paint

As an additive in paint, wollastonite improves the durability of the paint film, acts as a pH buffer, improves its resistance to weathering, reduces gloss, reduces pigment consumption, and acts as a flatting and suspending agent.[ citation needed ]

Plastic

In plastics, wollastonite improves tensile and flexural strength, reduces resin consumption, and improves thermal and dimensional stability at elevated temperatures. Surface treatments are used to improve the adhesion between the wollastonite and the polymers to which it is added.[ citation needed ]

Plastics and rubber applications were estimated to account for 25% to 35% of U.S. sales in 2009, followed by ceramics with 20% to 25%; paint, 10% to 15%; metallurgical applications, 10% to 15%; friction products, 10% to 15%; and miscellaneous, 10% to 15%. Ceramic applications probably account for 30% to 40% of wollastonite sales worldwide, followed by polymers (plastics and rubber) with 30% to 35% of sales, and paint with 10% to 15% of sales. The remaining sales were for construction, friction products, and metallurgical applications.[ citation needed ]

Substitutes

White acicular crystals of wollastonite (field of view 8 mm) from the Central Bohemia Region, Czech Republic Wollastonite-91985.jpg
White acicular crystals of wollastonite (field of view 8 mm) from the Central Bohemia Region, Czech Republic

The acicular nature of many wollastonite products allows it to compete with other acicular materials, such as ceramic fiber, glass fiber, steel fiber, and several organic fibers, such as aramid, polyethylene, polypropylene, and polytetrafluoroethylene in products where improvements in dimensional stability, flexural modulus, and heat deflection are sought.

Wollastonite also competes with several nonfibrous minerals or rocks, such as kaolin, mica, and talc, which are added to plastics to increase flexural strength, and such minerals as barite, calcium carbonate, gypsum, and talc, which impart dimensional stability to plastics.

In ceramics, wollastonite competes with carbonates, feldspar, lime, and silica as a source of calcium and silicon. Its use in ceramics depends on the formulation of the ceramic body and the firing method. [9]

Composition

In a pure CaSiO3, each component forms nearly half of the mineral by weight: 48.3% of CaO and 51.7% of SiO2. In some cases, small amounts of iron (Fe), and manganese (Mn), and lesser amounts of magnesium (Mg) substitute for calcium (Ca) in the mineral formula (e.g., rhodonite). [14] Wollastonite can form a series of solid solutions in the system CaSiO3-FeSiO3, or hydrothermal synthesis of phases in the system MnSiO3-CaSiO3. [13]

Geologic occurrence

Wollastonite skarn with diopside (green), andradite garnet (red) and vesuvianite (dark brown) from the Stanislaw mine near Szklarska Poreba, Izerskie Mountains, Lower Silesia, Poland. WEZUWIAN WOLLASTONIT ANDRADYT 2.jpg
Wollastonite skarn with diopside (green), andradite garnet (red) and vesuvianite (dark brown) from the Stanisław mine near Szklarska Poręba, Izerskie Mountains, Lower Silesia, Poland.

Wollastonite usually occurs as a common constituent of a thermally metamorphosed impure limestone, it also could occur when the silicon is due to metamorphism in contact altered calcareous sediments, or to contamination in the invading igneous rock. In most of these occurrences it is the result of the following reaction between calcite and silica with the loss of carbon dioxide: [13]

CaCO3 + SiO2 → CaSiO3 + CO2

Wollastonite may also be produced in a diffusion reaction in skarn, it develops when limestone within a sandstone is metamorphosed by a dike, which results in the formation of wollastonite in the sandstone as a result of outward migration of Ca. [13]

Structure

Unit cell of triclinic wollastonite-1A Wollastonite-cell.png
Unit cell of triclinic wollastonite-1A
Tetrahedra arrangement within the chains in pyroxenes compared to wollastonite SiO3 chains Pyrox vs Wollast.png
Tetrahedra arrangement within the chains in pyroxenes compared to wollastonite

Wollastonite crystallizes triclinically in space group P1 with the lattice constants a = 7.94  Å, b = 7.32 Å, c = 7.07 Å; α = 90,03°, β = 95,37°, γ = 103,43° and six formula units per unit cell. [17] Wollastonite was once classed structurally among the pyroxene group, because both of these groups have a ratio of Si:O = 1:3. In 1931, Warren and Biscoe showed that the crystal structure of wollastonite differs from minerals of the pyroxene group, and they classified this mineral within a group known as the pyroxenoids. [13] It has been shown that the pyroxenoid chains are more kinked than those of pyroxene group, and exhibit longer repeat distance. The structure of wollastonite contains infinite chains of [SiO4] tetrahedra sharing common vertices, running parallel to the b-axis. The chain motif in wollastonite repeats after three tetrahedra, whereas in pyroxenes only two are needed. The repeat distance in the wollastonite chains is 7.32 Å and equals the length of the crystallographic b-axis.

Molten CaSiO3 maintains a tetrahedral SiO4 local structure at temperatures up to 2000 °C. [18] The nearest neighbor Ca-O coordination decreases from 6.0(2) in the room temperature glass to 5.0(2) in the 1700 °C liquid, coincident with an increasing number of longer Ca-O neighbors. [19] [20]

See also

Related Research Articles

<span class="mw-page-title-main">Cement</span> Hydraulic binder used in the composition of mortar and concrete

A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Concrete is the most widely used material in existence and is behind only water as the planet's most-consumed resource.

<span class="mw-page-title-main">Mineral</span> Crystalline chemical element or compound formed by geologic processes

In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.

<span class="mw-page-title-main">Silicate</span> Any polyatomic anion containing silicon and oxygen

A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula [SiO(4-2x)−
4−x]
n, where 0 ≤ x < 2. The family includes orthosilicate SiO4−4, metasilicate SiO2−3, and pyrosilicate Si2O6−7. The name is also used for any salt of such anions, such as sodium metasilicate; or any ester containing the corresponding chemical group, such as tetramethyl orthosilicate. The name "silicate" is sometimes extended to any anions containing silicon, even if they do not fit the general formula or contain other atoms besides oxygen; such as hexafluorosilicate [SiF6]2−.Most commonly, silicates are encountered as silicate minerals.

<span class="mw-page-title-main">Olivine</span> Magnesium iron silicate solid solution series mineral

The mineral olivine is a magnesium iron silicate with the chemical formula (Mg,Fe)2SiO4. It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickly on the surface. For this reason, olivine has been proposed as a good candidate for accelerated weathering to sequester carbon dioxide from the Earth's oceans and atmosphere, as part of climate change mitigation. Olivine also has many other historical uses, such as the gemstone peridot, as well as industrial applications like metalworking processes.

<span class="mw-page-title-main">Amphibole</span> Group of inosilicate minerals

Amphibole is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain SiO
4 tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is Amp. Amphiboles can be green, black, colorless, white, yellow, blue, or brown. The International Mineralogical Association currently classifies amphiboles as a mineral supergroup, within which are two groups and several subgroups.

<span class="mw-page-title-main">Pyroxene</span> Group of inosilicate minerals with single chains of silica tetrahedra

The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula XY(Si,Al)2O6, where X represents calcium (Ca), sodium (Na), iron or magnesium (Mg) and more rarely zinc, manganese or lithium, and Y represents ions of smaller size, such as chromium (Cr), aluminium (Al), magnesium (Mg), cobalt (Co), manganese (Mn), scandium (Sc), titanium (Ti), vanadium (V) or even iron. Although aluminium substitutes extensively for silicon in silicates such as feldspars and amphiboles, the substitution occurs only to a limited extent in most pyroxenes. They share a common structure consisting of single chains of silica tetrahedra. Pyroxenes that crystallize in the monoclinic system are known as clinopyroxenes and those that crystallize in the orthorhombic system are known as orthopyroxenes.

<span class="mw-page-title-main">Slag</span> By-product of smelting ores and used metals

Slag is a by-product of smelting (pyrometallurgical) ores and recycled metals. Slag is mainly a mixture of metal oxides and silicon dioxide. Broadly, it can be classified as ferrous, ferroalloy or non-ferrous/base metals. Within these general categories, slags can be further categorized by their precursor and processing conditions. "Slag generated from the EAF process can contain toxic metals, which can be hazardous to human and environmental health".

<span class="mw-page-title-main">Calcium silicate</span> Chemical compound naturally occurring as the mineral larnite

Calcium silicate can refer to several silicates of calcium including:

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<span class="mw-page-title-main">Forsterite</span> Magnesium end-member of olivine, a nesosilicate mineral

Forsterite (Mg2SiO4; commonly abbreviated as Fo; also known as white olivine) is the magnesium-rich end-member of the olivine solid solution series. It is isomorphous with the iron-rich end-member, fayalite. Forsterite crystallizes in the orthorhombic system (space group Pbnm) with cell parameters a 4.75 Å (0.475 nm), b 10.20 Å (1.020 nm) and c 5.98 Å (0.598 nm).

<span class="mw-page-title-main">Enstatite</span> Pyroxene: magnesium-iron silicate with MgSiO3 and FeSiO3 end-members

Enstatite is a mineral; the magnesium endmember of the pyroxene silicate mineral series enstatite (MgSiO3) – ferrosilite (FeSiO3). The magnesium rich members of the solid solution series are common rock-forming minerals found in igneous and metamorphic rocks. The intermediate composition, (Mg,Fe)SiO
3, has historically been known as hypersthene, although this name has been formally abandoned and replaced by orthopyroxene. When determined petrographically or chemically the composition is given as relative proportions of enstatite (En) and ferrosilite (Fs) (e.g., En80Fs20).

<span class="mw-page-title-main">Silicate mineral</span> Rock-forming minerals with predominantly silicate anions

Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust.

<span class="mw-page-title-main">Rhodonite</span> Single chain manganese inosilicate (MnSiO3)

Rhodonite is a manganese inosilicate, with the formula (Mn, Fe, Mg, Ca)SiO3, and member of the pyroxenoid group of minerals, crystallizing in the triclinic system. It commonly occurs as cleavable to compact masses with a rose-red color (its name comes from Ancient Greek ῥόδον (rhódon) 'rose'), often tending to brown due to surface oxidation. The rose-red hue is caused by the manganese cation (Mn2+).

<span class="mw-page-title-main">Pyroxferroite</span>

Pyroxferroite (Fe2+,Ca)SiO3 is a single chain inosilicate. It is mostly composed of iron, silicon and oxygen, with smaller fractions of calcium and several other metals. Together with armalcolite and tranquillityite, it is one of the three minerals which were discovered on the Moon during the 1969 Apollo 11 mission. It was then found in Lunar and Martian meteorites as well as a mineral in the Earth's crust. Pyroxferroite can also be produced by annealing synthetic clinopyroxene at high pressures and temperatures. The mineral is metastable and gradually decomposes at ambient conditions, but this process can take billions of years.

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<span class="mw-page-title-main">Filler (materials)</span> Particles added to improve its properties

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<span class="mw-page-title-main">Carbonate–silicate cycle</span> Geochemical transformation of silicate rocks

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<span class="mw-page-title-main">Bustamite</span>

Bustamite is a calcium manganese inosilicate (chain silicate) and a member of the wollastonite group. Magnesium, zinc and iron are common impurities substituting for manganese. Bustamite is the high-temperature polymorph of CaMnSi2O6 and johannsenite is the low temperature polymorph. The inversion takes place at 830 °C (1,530 °F), but may be very slow.
Bustamite could be confused with light-colored rhodonite or pyroxmangite, but both these minerals are biaxial (+) whereas bustamite is biaxial (−).

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The pozzolanic activity is a measure for the degree of reaction over time or the reaction rate between a pozzolan and Ca2+ or calcium hydroxide (Ca(OH)2) in the presence of water. The rate of the pozzolanic reaction is dependent on the intrinsic characteristics of the pozzolan such as the specific surface area, the chemical composition and the active phase content.

References

PD-icon.svg This article incorporates public domain material from Wollastonite. United States Geological Survey.

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. ↑ Wollastonite, Mindat
  3. ↑ Wollastonite, Webmineral
  4. ↑ Wollastonite, Handbook of Mineralogy
  5. ↑ American Mineralogist, V. 79, pp. 134-144, 1994
  6. ↑ Virta, Robert; Van Gosen, Brad (January 27, 2015). "Mineral Resource of the Month: Wollastonite". Earth Magazine. American Geosciences Institute.
  7. ↑ Whitley, Sean; Halama, Ralf; Gertisser, Ralf; Preece, Katie; Deegan, Frances M.; Troll, Valentin R. (2020-10-18). "Magmatic and Metasomatic Effects of Magma–Carbonate Interaction Recorded in Calc-silicate Xenoliths from Merapi Volcano (Indonesia)". Journal of Petrology. 61 (4). doi: 10.1093/petrology/egaa048 . ISSN   0022-3530.
  8. ↑ William Alexander Deer; Robert Andrew Howie; J. Zussman (1992). An introduction to the rock-forming minerals. Longman Scientific & Technical. ISBN   978-0-470-21809-9.
  9. 1 2 Wollastonite, Mineral Commodity Summaries 2021
  10. 1 2 3 Robert L. Virta Wollastonite, USGS 2009 Minerals Yearbook (October 2010)
  11. ↑ National Academies of Sciences, Engineering, and Medicine (2019). "Chapter 6, Carbon mineralization of CO2". Negative Emissions Technologies and Reliable Sequestration: A Research Agenda (Report). Washington, DC: The National Academies Press. doi:10.17226/25259. ISBN   978-0-309-48452-7.{{cite report}}: CS1 maint: multiple names: authors list (link)
  12. ↑ Yan, Yongxue; Dong, Xiaohan; Li, Renshan; Zhang, Yankuan; Yan, Shaokui; Guan, Xin; Yang, Qingpeng; Chen, Longchi; Fang, Yunting; Zhang, Weidong; Wang, Silong (2023). "Wollastonite addition stimulates soil organic carbon mineralization: Evidences from 12 land-use types in subtropical China". Catena. 225. Bibcode:2023Caten.22507031Y. doi:10.1016/j.catena.2023.107031. S2CID   257202041.
  13. 1 2 3 4 5 Deer, Howie and Zussman. Rock Forming Minerals; Single Chain Silicates, Vol. 2A, Second Edition, London, The Geological Society, 1997.
  14. 1 2 Andrews, R. W. (1970). Wollastonite. London, Her Majesty's Stationery Office.
  15. ↑ Alter, Lloyd (August 15, 2019). "LafargeHolcim is selling CO2-sucking cement for precast, reduces emissions by 70 percent". TreeHugger. Retrieved 2019-08-17.
  16. ↑ Haque F, Santos RM, Dutta A, Thimmanagari M, Chiang YW (January 2019). "Co-Benefits of Wollastonite Weathering in Agriculture: CO2 Sequestration and Promoted Plant Growth". ACS Omega. 4 (1): 1425–1433. doi:10.1021/acsomega.8b02477. PMC   6374988 . PMID   30775646.
  17. ↑ Buerger, M. J. (1961). "The crystal structures of wollastonite and pectolite". Proceedings of the National Academy of Sciences. 47 (12): 1884–1888. Bibcode:1961PNAS...47.1884B. doi: 10.1073/pnas.47.12.1884 . JSTOR   71064. PMC   223235 . PMID   16578516.
  18. ↑ Benmore, C.J.; et al. (2010). "Temperature-dependent structural heterogeneity in calcium silicate liquids". Phys. Rev. B. 82 (22): 224202. Bibcode:2010PhRvB..82v4202B. doi:10.1103/PhysRevB.82.224202. hdl: 2160/8569 . S2CID   67808796.
  19. ↑ Skinner, L.B.; et al. (2012). "Structure of molten CaSiO3: Neutron diffraction isotope substitution with aerodynamic levitation and molecular dynamics Study". J. Phys. Chem. B. 116 (45): 13439–13447. doi:10.1021/jp3066019. PMID   23106223.
  20. ↑ Eckersley, M.C.; et al. (1988). "Structural ordering in a calcium silicate glass". Nature. 355 (6190): 525–527. Bibcode:1988Natur.335..525E. doi:10.1038/335525a0. S2CID   4360261.
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