Discussion of interface stability of large facets on solution grown crystals

O'Hara, S.; Tarshis, L.A.; Tiller, W. A.; Hunt, J. D.

doi:10.1016/0022-0248(68)90223-6

Cited by 32 publications

(13 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This vermiform or cellular growth was the last stage of growth of the chromian spinel, as it is always found as the outer rim. The faceted vermiform growth seen in Figures 7b and 7d is consistent with that described by O'Hara et al (1968) and Kirkpatrick (1975) for cellular growth. The Cr/(Cr + Al) of the vermiform rim is usually higher (Fisk & Bence 1980, present study), but the change in Cr/(Cr + Al) is small.…”

Section: Factors That Control Crystal Morphologysupporting

confidence: 89%

“…Many of the textural features described in the present study as vermiform are very similar to the cellular growth described for constitutional supercooling of metals and for faceting on quartz and sapphire crystals (O'Hara et al 1968). We suggest that whereas smaller crystals may respond to supercooling by a change of planar to edge or corner growth, larger planar faces may sometimes respond to increased supercooling by a change to cellular growth, such as that shown in Figures 2 and 4.…”

Section: Factors That Control Crystal Morphologysupporting

confidence: 80%

“…The metallurgical and material science literature contain many papers that deal with facet stability and the change from planar to cellular to dendritic growth (e.g., O'Hara et al 1968, Sekerka 1993, Federov & Zhivolub 1996. Many of the textural features described in the present study as vermiform are very similar to the cellular growth described for constitutional supercooling of metals and for faceting on quartz and sapphire crystals (O'Hara et al 1968).…”

Section: Factors That Control Crystal Morphologymentioning

confidence: 99%

See 2 more Smart Citations

Growth Forms and Composition of Chromian Spinel in Morb Magma: Diffusion-Controlled Crystallization of Chromian Spinel

Roeder

Poustovetov

Öskarsson

2001

The Canadian Mineralogist

View full text Add to dashboard Cite

Microphenocrysts of chromian spinel in glass from an East Pacific Rise lava and three Icelandic subglacial lavas show a variety of complex skeletal, hopper, vermiform and chain textures. These grains of chromian spinel are larger than those found in most basalts. Many crystals show significant zoning in Cr/(Cr + Al), and the variation in Cr/(Cr + Al) with respect to Fe 2+ /(Fe 2+ + Mg) is distinctive for each sample. The four samples are relatively primitive, with between 9 and 10 wt.% MgO in the glass. One very distinctive texture, a core surrounded by a vermiform rim, has been interpreted by a number of researchers as a reaction texture caused either by changes in pressure or magma mixing. The variety of chromian spinel textures, including the vermiform rim, has been duplicated in an experimental run using the sample from the East Pacific Rise. The sample was held at 1225°C for 67 hours and then cooled slowly over 8 hours to 1147°C. We conclude that the vermiform texture and the other chromian spinel textures in the experimental run and the lavas are growth textures and not reaction textures. The change in growth habit that produces the vermiform rim is interpreted as diffusion-controlled growth, leading to what metallurgists refer to as cellular growth. Chromian spinel is susceptible to diffusion-controlled growth because of the very large difference in concentration of Cr in the melt (0.02-0.06 wt.% Cr 2 O 3 ) and in chromian spinel (30-50 wt.% Cr 2 O 3 ) at equilibrium. Although the chromian spinel in the glass of each natural sample shows a large variation in Cr/(Cr + Al), and thus was not in equilibrium with the bulk melt, its Fe 2+ / (Fe 2+ + Mg) may have been close to equilibrium with the bulk melt before quenching. The chromian spinel crystallized over a span of hours to days before a rapid water quench upon eruption. The complex textures and zoning probably reflect the turbulent conditions during passage of the magma toward the Earth's surface.Keywords: chromian spinel, chromite, basalt, texture, vermiform, hopper, diffusion-controlled crystallization. SOMMAIREDes microphénocristaux de spinelle chromifère sont présents dans une matrice vitreuse d'une lave basaltique provenant de la ride Est-Pacifique et de trois échantillons de coulées mises en place sous un glacier en Icelande. Ces cristaux contiennent une variété de textures complexes en entonnoir, vermiformes et en chaînes; ils sont plus grossiers que ceux qui caractérisent la plupart des basaltes. Plusieurs cristaux montrent une zonation importante en Cr/(Cr + Al), qui varie de façon distincte avec Fe 2+ /(Fe 2+ + Mg) dans chaque échantillon. Les quatre échantillons sont relativement primitifs, le verre contenant entre 9 et 10% (poids) de MgO. On a généralement interprété la présence d'un coeur entouré d'un liseré vermiforme comme résultat d'une réaction suite à des changements en pression ou à un mélange de magmas. La diversité texturale du spinelle chromifère, y inclus la bordure vermiforme, a été reproduite dans un série d'expériences f...

show abstract

Section: Factors That Control Crystal Morphologysupporting

confidence: 89%

Section: Factors That Control Crystal Morphologysupporting

confidence: 80%

Section: Factors That Control Crystal Morphologymentioning

confidence: 99%

See 1 more Smart Citation

Growth Forms and Composition of Chromian Spinel in Morb Magma: Diffusion-Controlled Crystallization of Chromian Spinel

Roeder

Poustovetov

Öskarsson

2001

The Canadian Mineralogist

View full text Add to dashboard Cite

show abstract

“…O'Hara et al 1968). Formation of rod like radial inclusions of silicate melts in magmatic minerals is a well known phenomenon (Roedder 1984, Figs.…”

Section: Garnets From Mageroymentioning

confidence: 99%

Morphological instabilities during rapid growth of metamorphic garnets

Jamtveit

Andersen

1992

Phys Chem Minerals

View full text Add to dashboard Cite

Abstract. Hydrothermal grossular-andradite garnets from contact aureoles in the Oslo region show morphological transitions from planar via cellular to hopper-like structures. Dodecahedral surfaces {110} dominate during the planar growth stage, whereas the stable crystal faces, developed during the cellular and hopper stages also includes the ikositetrahedron {211} and possibly the hexoctahedron {321}. Faceted cells develope when initially 'wavy' perturbations on the dodecahedral surfaces become tangential to lower-index planar surfaces.Inclusion patterns and morphologies of almandinerich garnets from Mageroy (northernmost Norway) that formed during a period of rapid heating, suggest an early stage of cellular growth followed by planar growth. The morphological transitions suggest that the hydrothermal garnets experienced an increase in the overstepping of the garnet precipitation reaction at some stage during their growth whereas the opposite was the case during growth of the Mageroy garnets. The present observations put constraints on the garnet growth rates and emphasize the importance of growth kinetics during metamorphic processes.

show abstract

“…[1,2]. These studies provide an equation for the uniform undercooling on a stationary facet, bounded by rough surfaces, as a function of its geometry, relevant surface energies, and entropy of fusion.…”

Section: Introductionmentioning

confidence: 99%