gilbertiten.
/ˈɡɪlbətʌɪt/, U.S. /ˈɡɪlbərˌtaɪt/ Mineralogy.
A variety of muscovite occurring in small, often silky scales, varying in colour from whitish-yellow to yellowish-green.
ΘΚΠ
the world > the earth > minerals > types of mineral > silicates > phyllosilicate > [noun] > kandites > kaolinite > varieties
kaolin1728
nacrite1808
pholerite1826
gilbertite1830
tuesite1837
china-clay1840
teratolite1868
1830 Gentleman's Mag. June 544/1 A paper was read [to the Royal Society on June 10], containing descriptions..of twenty new species of minerals..by Tho. Thomson... One of these minerals is named by the author Wollastonite,..and another Gilbertite, in honour of the president of the Royal Society.
1835 C. U. Shepard Treat. Mineral. II. ii. 228 Gilbertite..occurs at St. Austle in Cornwall.
1868 J. D. Dana Syst. Mineral. (ed. 5) Suppl. 798 Gilbertite,..Perhaps an impure kaolinite.
1905 F. W. Rudler Handbk. Coll. Minerals Brit. Islands 27 Gilbertite appears to be an alteration-product of felspar, and pseudomorphs of gilbertite in the form of orthoclase are known.
1969 U.S. Geol. Surv. Professional Paper No. 608A. B69/1 The gilbertite granite in the St. Austell pluton, Cornwall, contains an average of approximately 1.5 percent fluorite.
2014 C. M. Bristow in J. Cassar et al. Stone Hist. Buildings 103/1 A greenish mica, often referred to by the field term ‘gilbertite’, occurs in greisened areas and is similar in composition to muscovite but contains more hydroxyls in the lattice.
This entry has been updated (OED Third Edition, December 2018; most recently modified version published online March 2022).
<
n.1830