portlanditen.
/ˈpɔːtləndʌɪt/, U.S. /ˈpɔrtlənˌdaɪt/ Mineralogy.
A mineral of the hexagonal crystal system that is a form of calcium hydroxide that occurs naturally as minute colourless plates and is a common product of the hydration of Portland cement.
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the world > the earth > minerals > types of mineral > oxides and hydroxides > [noun] > hydroxides > others
gibbsite1822
pyrochroite1868
portlandite1933
hydrocalumite1934
nordstrandite1962
wickmanite1967
tetrawickmanite1973
1933 C. E. Tilley in Mineral. Mag. 23 420 The occurrence of Ca(OH)2 as a well-defined species is the contact-zone of Scawt Hill [in County Antrim] merits a new mineral name, and in view of its occurrence as a common product of hydration of Portland cement, and furthermore as crystals from this source have provided the first reliable physical and optical data on crystalline Ca(OH)2, it is fitting that the mineral name should bear record of these facts. The name Portlandite is accordingly proposed.
1977 Sci. Amer. Aug. 84 In a hardened cement this gel..occupies about 70 percent by volume of the hydrated material... The major part of the other crystalline products consists of calcium hydroxide (portlandite).
1999 I. Kostov & R. I. Kostov Crystal Habits Minerals vi. 178 Fluorite... Cubic crystals have been obtained in alkaline medium together with portlandite, Ca(OH)2.
This entry has been updated (OED Third Edition, December 2006; most recently modified version published online March 2022).
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n.1933