...D. R. Veblen; C. W. Burnham Abstract The crystal structures of jimthompsonite, clinojimthompsonite, and chesterite have been solved and refined using three-dimensional X-ray intensity data. Jimthompsonite and clinojimthompsonite contain I-beams composed of triple silicate chains and wide octahedral...

... reactions include amphibole, clinojimthompsonite, chain-width disordered pyribole, and several sheet silicates. Textural considerations indicate that there are a number of different paths for pyroxene hydration reactions. These include the simple paths pyroxene → amphibole, pyroxene → clinojimthompsonite...

... clinojimthompsonite (Na-cjt) with existing data for various common minerals (i.e., enstatite, talc, anthophyllite, and chrysotile). We also present new experimental data to show that Na-cjt should form stably at typical metamorphic conditions of 0.2 GPa and 450 °C. Ion-activity vs. pH diagrams calculated at 100–300...

... to triple I beam zippers, including pyroxene slabs, to longer NCP polysomes up to 15-I beam chains. Clinojimthompsonite (Cjim) is observed for the first time within magnetite. Although no discrete polysomes could be defined, the NCP-amphibole intergrowths have compositions between Mg-Fe amphiboles and Cjim...

.... The cell parameters of the minerals are diagnostic: (1) jimthompsonite is orthorhombic, Pbca, a = 18.6, b = 27.2, с = 5.30A; (2) clinojimthompsonite is monoclinic, C 2/ c, a = 9.87, b = 27.2, с = 5.32A, β = 109.5°; (3) chesterite is orthorhombic, A 2 1 ma, a = 18.6, b = 45.3, с = 5.30A; (4) an unnamed...

...Figure 1. ( a and b ) Atom filling models for crystal structures of ferro-tschermakite and clinojimthompsonite projected onto [001] showing occupancy of cation sites as marked. Crystallographic information data from Hawthorne and Grundy (1973) and Veblen and Burnham (1978) . The two building...

..., and were named jimthompsonite [Mg 10 Si 12 O 32 (OH) 4 ; Pbca ] and chesterite [Mg 17 Si 20 O 54 (OH) 6 ; A 2 1 ma ] ( Veblen and Burnham 1978a , 1978b ; Veblen et al. 1977 ). Their monoclinic polymorphs are, respectively, clinojimthompsonite ( C 2/ c ) and an unnamed mineral ( A 2/ m ) (e.g., Droop...

...F ig . 23. The I-beam of clinojimthompsonite projected on to (100) and showing tetrahedra T (1,2,3), the ribbon of octahedra and the three distinct potential sites for molecular H 2 O W (1,2,3). The water sites lie in the channel in a plane parallel to (100) and are 3 Å apart. There is one...

... silicates have not yet been synthesized, this study focused on the Na-analogue to clinojimthompsonite (Na-cjt), which forms readily in a laboratory setting. Synthetic Na-cjt was characterized using electron microscopy and microanalysis, thermogravimetric analysis, infrared spectroscopy, and loss on ignition...

... experiment, a calcian clinojimthompsonite domain extending 15 unit cells along the b axis was observed. The sample after 582 h and five retreatments shows, on average, 3.5% true solid solution with Mg expressed as the Mg-cummingtonite (MC) component after correction for the presence of CMFs. This sample...

... amphibole of grunerite composition containing no detectable amount of Cl but intergrown with submicrometer-sized slabs of Cl-rich annite (2.8 wt%), Fe-rich talc, Fe-rich clinojimthompsonite, and very wide chain silicate. TEM-AEM study of prograde hastingsite and biotite suggests that Cl is dissolved...

...) with composition near that of talc, (Mg,Fe) 3 Si 4 O 10 (OH) 2 . The calculations were performed using results of the structure refinements of two orthopyroxenes (Opx), clinoenstatite (Cpx), twoampiboles (anthophyllite = An, cummingtonite = Cu), chesterite (Ch), jimthompsonite (Jt), clinojimthompsonite, and talc...