The crystal structure of the monoclinic pyroxenes

The Clinopyroxenes of the Garbh Eilean Sill, Shiant Isles

“…Warren and Briscoe (1931) showed that acmite, jadeite, spodumene, augite, diopside, hedenbergite, and clinoenstatite had similar structures typified by diopside. They suggested as a general formula for the monoclinic pyroxenes:-m Ytt~m (Si, A1) 2 (O, OH, F) 6 where m = 1 or 0 0 and X = Na, Ca, (K), (Mn), and Y = Mg, Fe 2+ , Fe 3 +, Al, Ti, Mn.…”

Zur Struktur des β-Wollastonits des Maddrellschen Salzes und des Natriumpolyarsenats

“…1), sondern aueh von asymmetrischen Baueinheiten, sofern diese entsprechend einer 2-ziihligen Sehraubenachse angeordnet sind. Aueh die Symmetriebeziehungen zwisehen den Intensit~iten der Reflexe mit geradem k des triklinen flWollastonits, die schon Warren & Biscoe (1931) Die Patterson-Maxima der xz-Projektionen der drei Substanzen liegen durehaus analog, wobei sich die As-As-Gipfel durch ihr besonders grosses Gewicht eindeutig abzeichneten. Schon Lage und Gewicht dieser Maxima gestatteten, jede Ringanordnung auszuschliessen und fiihrten auf ziemlich stark geknickte Ketten.…”

On Pectolite

“…The closest agreement is shown by wollastonite and the artificial manganese wollastonite, vogtite, in the setting recently proposed by Bowen (1933). Wollastonite has six molecules in the unit cell (Warren and Biscoe, 1931); presumably vogtite has the same number. The entry of manganese into the wollastonite structure has very little effect on the geometrical elements.…”

“…On the contrary, Greg and Lettsom (1858) commented on the hemihedral arrangement of the prisms; later, Goodchild (1903) reached the conclusion that pectolite is not monoclinic but triclinic, with elements which could not be completely determined with the material available. Pectolite is thus known with certainty to have forms in two zones whose axes are apparently at right angles; the existence and relations of forms in other zones are uncertain and the generally accepted monoclinic symmetry is speculative.In a recently completed study of the morphology of wollastonite 2 ) a crystallographic discussion of form-rich crystals from Crestmore, California, led unequivocally to triclinic elements closely comparable to those proposed for wollastonite by Warren and Biscoe (1931) on the basis of X-ray analysis. Since these authors also showed that pectolite from Norway is likewise triclinic, with elements similar to those of wollastonite, it was to be expected that the morphological data on pectolite would be found to agree with the röntgenographic results.…”

“…In a recently completed study of the morphology of wollastonite 2 ) a crystallographic discussion of form-rich crystals from Crestmore, California, led unequivocally to triclinic elements closely comparable to those proposed for wollastonite by Warren and Biscoe (1931) on the basis of X-ray analysis. Since these authors also showed that pectolite from Norway is likewise triclinic, with elements similar to those of wollastonite, it was to be expected that the morphological data on pectolite would be found to agree with the röntgenographic results.…”