.... Nagashima M. , Imaoka T. , Fukuda C. and Pettke T. ( 2018 ) Relationship between cation substitution and hydrogen-bond system in hydrous pyroxenoids with three-periodic single-chains of SiO 4 tetrahedra: pectolite, murakamiite, marshallsussmanite, serandite and tanohataite . European...

... with layers containing the NaO 4 (OH)(H 2 O) 2 polyhedra. The I -beam topology and the T–O–T stacking pattern present in nolzeite is similar to that found in other chain silicate minerals, specifically steedeite, as well as pyroxenoids of the pectolite (NaCa 2 [Si 3 O 8 OH])–sérandite (NaMn 2 [Si 3...

...R. H. Mitchell; M. D. Welch; A. R. Kampf; A. K. Chakhmouradian; J. Spratt Abstract The new pyroxenoid barrydawsonite-(Y) occurs at the Merlot Claim, North Red Wine Pluton, Labrador, Canada (62°32′38.54″ W; 54°08′1.37″ N). The host rock is a metamorphosed eudialyte syenite consisting of eudialyte...

..., manganiferous, pyroxene-pyroxenoid, Ca-rich garnet alteration assemblages. The latter include hedenbergite, pyroxferroite-pyroxmangite, fayalite, calcic almandine, quartz, and apatite. Immobile element concentrations and mass balance considerations demonstrate that rocks with the pyroxene-pyroxenoid-garnet...

...Kenneth J. T. Livi; David R. Veblen Abstract Two occurrences of johannsenite partially altered to pyroxenoid minerals were studied by X-ray emission analytical electron microscopy in the context of the pyroxene-wollas-tonite polysomatic series in order to determine the relationships between...

...Ross J. Angel; Charles W. Burnham Abstract Previous discussions of the pyroxenoid and clinopyroxene crystal structures have noted the polysomatic relationship between them, in which pyroxenoids with chain periodicities greater than three contain both pyroxeno-like (P) and wollastonite-like (W...

...Donald R. Peacor; Pete J. Dunn; John S. White; Joel D. Grice; Peter H. Chi Abstract Lithiomarsturite, ideally LiCa 2 Mn 2 HSi 5 O 15 , is a new member of the p-p (pectolite-pyroxene) series of pyroxenoids (hydropyroxenoids). It has a structure based on fünferket-ten , but chain-periodicity faults...

...David R. Veblen Abstract A specimen of the CaMn clinopyroxene johannsenite that has partially reacted to Mn pyroxenoids has been studied with high-resolution transmission electron microscopy (HRTEM), electron diffraction, and single-crystal X-ray methods. The primary johannsenite is structurally...

...Friedrich Liebau Abstract In pyroxenoids containing cationic hydrogen [pectolite, schizolite, serandite, unnamed Ca(Sc,Fe 3+ )H[Si 3 O 9 ], synthetic Cd 2 NaH[Si 3 O 9 ], nambulite, Li-hydrorhodonite, santaclaraite, and babingtonite] the identity periods of the silicate chains are approximately...

...C. T. Prewitt; Donald R. Peacor Abstract The classification of the crystal structures of the pyroxenes and pyroxenoids according to the repeat unit of the silicate chain is well-known. This system does not, however, differentiate between structures which contain similar types of chains. For example...

...Richard M. Thompson; Hexiong Yang; Robert T. Downs Abstract A hypothetical ideal wollastonite with regular octahedra and T3 tetrahedron is presented and used to compare and contrast the pyroxenes and pyroxenoids. While clinopyroxenes have close-packed arrangements of oxygen anions, several lines...

...D. Andrault; J. P. Itie; F. Farges Abstract The CaGeO 3 and SrGeO 3 perovskites and CaGeO 3 , SrGeO 3 , and MnGe0 3 pyroxenoids have been studied at high-temperature by X-ray diffraction (XRD) and X-ray absorption fine-structure spectroscopy (XAFS). The diffraction studies show that the back...

... is partially occupied. Five crystallographically independent octahedral sites are occupied by Mn (mainly Mn 2+ with 10–20 % Mn 3+ ), with additional small amounts of Ca and V 3+ . An undulating pyroxenoid-like chain is built by five SiO 4 tetrahedra. A sixth tetrahedron, forming a branch of the chain...