Gyrolite: Its Crystal Structure and Crystal Chemistry
- 1 June 1988
- journal article
- Published by Mineralogical Society in Mineralogical Magazine
- Vol. 52 (366), 377-387
- https://doi.org/10.1180/minmag.1988.052.366.09
Abstract
The crystal structure of gyrolite from Qarusait, Greenland, was solved and refined with the space group P and cell parameters a = 9.74(1), b = 9.74(1), c = 22.40(2)Å, α = 95.7(1)°, β = 91.5(1)°, γ = 120.0(1)°. The structure is built up by the stacking of the structural units already found in the crystal structure of reyerite (Merlino, 1972, 1988), namely tetrahedral sheets S1 and S2 and octahedral sheets O. The tetrahedral and octahedral sheets are connected by corner sharing to give rise to the complex layer which can be schematically described as 1OS2, where S2 and , as well as O and , are symmetry-related units. Successive complex layers with composition [Ca14Si23AlO60(OH)8]-5 are connected through an interlayer sheet made up by calcium and sodium cations and water molecules.The unit cell content NaCa16Si23AlO60(OH)8·14H2O, determined by the structural study, was confirmed by a chemical analysis, apart from the indication of a somewhat larger water content. The crystal chemistry of gyrolite is discussed on the basis of the present structural results and the chemical data given in the literature for gyrolite from different localities: the crystal chemical formula which accounts for most gyrolite samples is Ca16Si24O60(OH)8·(14+x)H2O, with 0 ⩽ x ⩽ 3.Stacking disorder, twinning and polytypic variants in gyrolite, as well as the structural relationships of gyrolite with truscottite, reyerite, fedorite and the synthetic phases K and Z are described and discussed.Keywords
This publication has 10 references indexed in Scilit:
- Gyrolite: Its Crystal Structure and Crystal ChemistryMineralogical Magazine, 1988
- Ca7Si16O40H2, a new calcium silicate hydrate phase of the truscottite groupCement and Concrete Research, 1981
- Truscottite: composition and ionic substitutionsMineralogical Magazine, 1979
- Zeolites and associated secondary minerals in the Deccan Traps of Western IndiaMineralogical Magazine, 1974
- New Tetrahedral Sheets in ReyeriteNature Physical Science, 1972
- Gyrolites from Irakawa, Yamagata Prefecture, and Otemo, Niigata Prefecture.The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists, 1969
- X-ray scattering factors computed from numerical Hartree–Fock wave functionsActa Crystallographica Section A, 1968
- Hydrothermal Reactions between Calcium Hydroxide and Amorphous Silica: the Reactions between 180 and 220°The Journal of Physical Chemistry, 1957
- Über Hydrogensilicate. IV. Das Calcium‐trihydrogenmonosilicat Ca[OSi(OH)3]2 und seine Umwandlung in das Calciumtetrahydrogendisilicat Ca[Si2O3(OH)4]Zeitschrift für anorganische und allgemeine Chemie, 1955
- Formation of hydrated calcium silicates at elevated temperatures and pressuresJournal of Research of the National Bureau of Standards, 1938