Tobermorite is a calcium silicate hydrate mineral with chemical formula: Ca5Si6O16(OH)2·4H2O or Ca5Si6(O,OH)18·5H2O.
| Tobermorite | |
|---|---|
 Crystalline mass of tobermorite | |
| General | |
| Category | Silicate mineral, Calcium silicate hydrate |
| Formula (repeating unit) | Ca5Si6O16(OH)2·4H2O, or; Ca5Si6(O,OH)18·5H2O |
| IMA symbol | Tbm[1] |
| Strunz classification | 9.DG.10 |
| Crystal system | Orthorhombic |
| Crystal class | Disphenoidal (222) H-M symbol: (2 2 2) |
| Space group | C2221 (no. 20) |
| Unit cell | a = 11.17 Å, b = 7.38 Å c = 22.94 Å; β = 90°; Z = 4 |
| Identification | |
| Formula mass | 702.36 g/mol |
| Color | Pale pinkish white, white, brown |
| Crystal habit | As minute laths; fibrous bundles, rosettes or sheaves, radiating or plumose, fine granular, massive. |
| Cleavage | {001} Perfect, {100} Imperfect |
| Mohs scale hardness | 2.5 |
| Luster | Vitreous, silky in fibrous aggregates |
| Streak | White |
| Diaphaneity | Translucent to translucent |
| Specific gravity | 2.423 – 2.458 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.570 nβ = 1.571 nγ = 1.575 |
| Birefringence | δ = 0.005 |
| Ultraviolet fluorescence | Fluorescent, Short UV:weak white to yellow, Long UV:weak white to yellow |
| References | [2][3][4] |
Two structural varieties are distinguished: tobermorite-11 Å and tobermorite-14 Å. Tobermorite occurs in hydrated cement paste and can be found in nature as an alteration mineral in metamorphosed limestone and in skarn. It has been reported to occur in the Maqarin Area of north Jordan and in the Crestmore Quarry near Crestmore Heights, Riverside County, California.
Tobermorite was first described in 1880 for an occurrence in Scotland, on the Isle of Mull, around the locality of Tobermory.[3][5]
Use in Roman concrete
editAluminum-substituted tobermorite is understood to be a key ingredient responsible for the longevity of ancient undersea Roman concrete. The volcanic ash that Romans used for construction of sea walls contained phillipsite, and an interaction with sea water caused the crystalline structures in the concrete to expand and strengthen, making that material substantially more durable than modern concrete when exposed to sea water.[6][7][8]
Cement chemistry
editTobermorite is often used in thermodynamical calculations to represent the pole of the most evolved calcium silicate hydrate (C-S-H). According to its chemical formula, its atomic Ca/Si or molar CaO/SiO2 (C/S) ratio is 5/6 (0.83). Jennite represents the less evolved pole with a C/S ratio of 1.50 (9/6).
See also
edit- Other calcium silicate hydrate (C-S-H) minerals:
- Afwillite – Nesosilicate alteration mineral also sometimes found in hydrated cement paste
- Gyrolite – Rare phyllosilicate mineral crystallizing in small spheres
- Jennite – Inosilicate alteration mineral in metamorphosed limestone and in skarn
- Thaumasite – Complex calcium silicate hydrate mineral
- Xonotlite – Inosilicate mineral
- Other calcium aluminium silicate hydrate, (C-A-S-H) minerals:
- Hydrogarnet
- Hydrogrossular
- Hydrotalcite
- Katoite
- Tacharanite (Ca12Al2Si18O33(OH)36)
References
edit- ^ 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.
- ^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Tobermorite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 27 July 2022.
- ^ a b Mineralogy Database, Mindat.org, retrieved 27 July 2022
- ^ Barthelmy, David (2014). "Lavendulan Mineral Data". Webmineral.com. Retrieved 27 July 2022.
- ^ Scottish physician and amateur mineralogist Matthew Forster Heddle (1828–1897) first described tobermorite in: Heddle (1880). "Preliminary notice of substances which may prove to be new minerals. Part second". Mineralogical Magazine and Journal of the Mineralogical Society. 4: 117–123. doi:10.1180/minmag.1880.004.18.04. See pp. 119–121.
- ^ Ancient Romans made world’s ‘most durable’ concrete. We might use it to stop rising seas, Washington Post, Ben Guarino, July 4, 2017. Retrieved July 5, 2017.
- ^ Ancient lessons: Roman concrete durable, green, Jim Destefani, ed., Ceramic Tech Today, The American Ceramic Society, June 7, 2013
- ^ Jackson, Marie D.; Mulcahy, Sean R.; Chen, Heng; Li, Yao; Li, Qinfei; Cappelletti, Piergiulio; Wenk, Hans-Rudolf (2017). "Phillipsite and Al-tobermorite mineral cements produced through low-temperature water-rock reactions in Roman marine concrete". American Mineralogist. 102 (7): 1435–1450. Bibcode:2017AmMin.102.1435J. doi:10.2138/am-2017-5993CCBY. ISSN 0003-004X.
Further reading
edit- American Mineralogist (1954) 39, 1038.
- Taylor, H. F. W. (June 1959). "The transformation of tobermorite into xonotlite". Mineralogical Magazine and Journal of the Mineralogical Society. 32 (245): 110–116. Bibcode:1959MinM...32..110T. doi:10.1180/minmag.1959.32.245.03. eISSN 2515-821X. ISSN 0369-0148.
- Abdul-Jaber, Q.H.; Khoury, H. (1998), "Unusual mineralisation in the Maqarin Area (North Jordan) and the occurrence of some rare minerals in the marbles and the weathered rocks", Neues Jahrb. Geol. Paläontol. Abh., vol. 208, no. 1–3, pp. 603–629, doi:10.1127/njgpa/208/1998/603
- Chen, Jeffrey J.; Jeffrey J. Thomas; Hal F.W. Taylor; Hamlin M. Jennings (2004). "Solubility and structure of calcium silicate hydrate". Cement and Concrete Research. 34 (9): 1499–1519. CiteSeerX 10.1.1.568.4216. doi:10.1016/j.cemconres.2004.04.034. ISSN 0008-8846.
- Coleman, Nichola J. (2011). "11 Ä tobermorite ion exchanger from recycled container glass". International Journal of Environment and Waste Management. 8 (3–4): 366–382. doi:10.1504/IJEWM.2011.042642.
- Currie, J. (1905). "Note on some new localities for gyrolite and tobermorite". Mineralogical Magazine. 14 (64): 93–95. Bibcode:1905MinM...14...93C. doi:10.1180/minmag.1905.014.64.06.
- Eakle, Arthur S. (1927). "Famous mineral localities: Crestmore, Riverside County, California". American Mineralogist. 12: 319–321. Retrieved 2009-11-01.
- Kikuma, J.; Tsunashima M.; Ishikawa T.; Matsuno S.; Ogawa A.; Matsui K.; Sato M. (2009). "Hydrothermal formation of tobermorite studied by in situ X-ray diffraction under autoclave condition". Journal of Synchrotron Radiation. 16 (5): 683–686. doi:10.1107/s0909049509022080. PMID 19713643.
- McConnell, J.D.C. (1954). "The hydrated calcium silicates riversideite, tobermorite and plombierite". Mineralogical Magazine. 30 (224): 293–305. Bibcode:1954MinM...30..293M. doi:10.1180/minmag.1954.030.224.02. S2CID 94792892.
- Merlino, S.; Bonaccorsi E.; Armbruster T. (1999). "Tobermorites: Their real structure and order-disorder (OD) character, Sample: 9 Angstrom". American Mineralogist. 84 (10): 1613–1621. doi:10.2138/am-1999-1015. S2CID 58927981.
- Merlino, S.; Bonaccorsi E.; Armbruster T. (2001). "The real structure of tobermorite 11A: normal and anomalous forms, OD character and polytypic modifications (Note: MDO2 – synchrotron radiation source. Locality: Bascenov, Urals, Russia)". European Journal of Mineralogy. 13 (3): 577–590. Bibcode:2001EJMin..13..577M. doi:10.1127/0935-1221/2001/0013-0577.
- Naomichi, Hara (2000). "Formation of jennite and tobermorite from amorphous silica". J. Soc. Inorg. Mater. Japan. 7 (285): 133–142. ISSN 1345-3769. Archived from the original on 2012-02-17. Retrieved 2009-02-04.
External links
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