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<p> Eight new scapolite analyses are presented. Determinations of refractive index, specific gravity, and lattice parameters are examined in conjunction with data available in five recent analyses. Particular reference is made to the regular variation of per cent Cl₂, CO₂ and SO₃ as a function of mole per cent meionite and the relation of these components to scapolite stability. End member formulae describing the composition of scapolite are developed. </p> <p> These scapolite samples are used in conjunction with synthetic plagioclase standards to obtain forty three electron microprobe analyses of scapolite-plagioclase pairs and twenty seven separate analyses of scapolite. The former analyses indicate that scapolite from amphibolite and granulite facies is generally more calcium-rich than the coexisting plagioclase. </p> <p> A petrographic study indicates that scapolite associated with the above grade of metamorphism is indicative of a volatile rich environment typified by the amphibolite facies by the assemblage sphene-pyroxene-scapolite. </p> / Thesis / Master of Science (MSc)

Thesis (Ph. D.)--University of Wisconsin--Madison, 1988. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 169-188).

<p> The aureole surrounding the Loon Lake pluton, notable for the presence of scapolite, is situated in an upper amphibolite facies terrane in the Grenville Province of southern Ontario. Four distinct scapolite-bearing parageneses are found to surround the pluton in more or less concentric zones. Furthest from the pluton a clinopyroxene-scapolite gneiss grades into Ca-amphibole gneiss, Ca-amphibole-biotite gneiss and biotite gneiss. Scapolite is also found in the marbles surrounding the aureole, as well as in all gneisses of the aureole. As the mineralogy of the gneisses change from clinopyroxene through biotite, the textures grade from granoblastic polygonal to a granoblastic polygonal texture modified by abundant acicular and platy minerals. </p> <p> As the pluton is approached, scapolite often assumes a ragged fine-grained nature with alteration to sericite. The whole rock chemistry is characteristic of that derived from a mixture of intermediate volcanics (latite) and carbonate-evaporites. This sequence was undoubtedly deposited in a shallow marine environment. Subsequent metamorphism to upper amphibolite facies produced a band of clinopyroxene gneiss. As the Loon Lake pluton was emplaced increasing temperature and volatiles in an aqueous solution caused the clinopyroxene-scapolite gneiss to undergo retrograde metamorphism and formed the Ca-amphibole, Ca-amphibole-biotite and biotite gneisses. </p> <p> Studies of mineral chemistry indicate that the minerals coexist in equilibrium and that they are related, to some degree, to whole rock composition. As the retrograde metamorphsim occurred elements within the minerals redistributed themselves according to the nature of the new phases produced. Finally, the partitioning between phases followed the ideal binary solution model. Chlorine is found to be partitioned between scapolite, Ca-amphibole and biotite, and all three phases contain chlorine, the relative amounts present being controlled by the crystal structure of the minerals. The relation of Lin and Burley (1973a) between lattice parameter and scapolite composition is confirmed. </p> / Thesis / Master of Science (MSc)

A scapolite-hornblende-biotite schist from the Grenville province of the Canadian Shield has been analysed for Tl by an atomic absorption technique with a high sensitivity. K, Rb and some major oxides were determined by wet chemistry. Tl, K/Rb, K/Tl and Tl/Rb were compared to several other rocks and for this report were found to be 432ppb, 429, 4.85x10³ and 88.4x10⁻³ respectively. These values are similar to those quoted for other rocks. / Thesis / Bachelor of Science (BSc)

The systematic investigation of the x-ray diffraction symmetry of scapolites covering the whole range of solid solution show that all scapolites possess space group P4(2)/n, except the pure end-members, marialite and meionite, which will possess space group I4/m, if they exist. The intensity of the weak superlattice reflections violating the body-centred symmetry, continuously increases from zero at the marialite end-member as Me% increases, reaches a maximum around 37%+/-2% Me then approximately symmetrically decreases to 75% Me followed by a slower decrease to zero at the meionite end-member. Hence, all the intermediate scapolites of the marialite-meionite series actually have a pseudosymmetric structure, i. e., a pseudobody-centred structure, and as the chemical composition approaches both end-members, the scapolite structure approaches the structure with a body-centred lattice. The weak super-lattice reflections are directly related to the following two correlated factors: (1) the relative order-disorder of A1 and Si distribution in the tetrahedral framework, and (2) the structural distortion from the body-centred symmetry. Accompanied with the above facts is the systematic deviation of cell dimensions from the linear regression in such a way that the further the structure deviates from the body-centred symmetry, the smaller the cell volume and the a(o) become relative to the evaluated one from the linear regression. Scapolites are regarded as a continuous, perfect solid solution with a long-range disordering, and unlikely to be composed of submicroscopic twins or different domains. The structural analyses and refinements of three scapolites (ON8, 20% Me; XL, 52% Me; ON45, 93% Me) have been carried out by using 3-dimensional intensity data collected by integrated precession film techniques (ON8, ON45) and an automated single-crystal diffractometer (XL), and using the full-matrix least0squares method. The result has clarified the ambiguities arising from the previous studies and showed that the crystal structure is essentially continuous along the marialite-meionite series, with a slight structural variation as a function of chemical composition and ordering of Al, Si. Several important quantitative relationships regarding the crystal structure and crystal chemistry of the scapolite solid solution series have been established, namely, (1) the relationship between the superlattice intensity r(ΣI(h+k+l=2n+1)/ΣI(h+k+l=2n)) and the chemical index % Me. (2) the exponential relationship between the superlattice intensity ration r and the atomic displacement from the mirror plane consistent with the space group I4/m. (3) The linear relationship between the superlattice intensity ratio r and the difference of Al occupancy between T2 and T3 sites. (4) The Al occupancy (%) of tetrahedral sites as a function of the chemical composition of scapolites. The ordering of Al-Si, the c-axis displacement of (Ca, Na), the tilting of CO3 and the relative amount of CO3 and Cl in the same scapolite are all inter-related. The mechanism to cause all such related structural phenomena and even the abnormal stoichiometry of scapolite can all be interpreted in terms of the internal strain created by the two greatly different anions, Cl- and CO3-,sharing the same set of equivalent sites. / Thesis / Doctor of Philosophy (PhD)