Entwicklung der Krystallformen

Goldschmidt, Victor

doi:10.1007/978-3-642-99453-1_2

Cited by 27 publications

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“…Structural and morphological data for vesuvianite (Goldschmidt 1918, Allen & Burnham 1992, Armbruster & Gnos 2000a suggest that whiskers of vesuvianite are anomalous. This peculiar habit is related to specific conditions and mechanism of growth.…”

Section: Conditions Of Growth and Mechanism Of Formation Of The Vesuvmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…In skarns, vesuvianite usually develops prismatic or bipyramidal crystals with rather simple forms: {100}, {110}, {101}, {001} (Goldschmidt 1918, Lyakhovich 1954, Chukhrov et al 1972. The crystal morphology is more complicated in rodingitic vesuvianite, which is commonly more acicular (Goldschmidt 1918, Chukhrov et al 1972, Arem 1973, Antonova & Goylo 1999. In this study, we describe the relation among morphology, crystal structure, and composition of whiskers of high-fluorine, high-symmetry, low-temperature vesuvianite from cavities of an altered magnesian skarn in the Tas-Khayakhtakh Mountains of Polar Yakutia, in Russia.…”

Section: Introductionmentioning

confidence: 99%

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MORPHOLOGY, COMPOSITION AND STRUCTURE OF LOW-TEMPERATURE P4/nnc HIGH-FLUORINE VESUVIANITE WHISKERS FROM POLAR YAKUTIA, RUSSIA

Galuskin

Armbruster

Malsy

et al. 2003

The Canadian Mineralogist

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Whiskers and needles of F-rich vesuvianite were found together with diopside in cavities of an altered magnesian skarn in the Tas-Khayakhtakh Mountains of Polar Yakutia, in Russia. The acicular crystals are strongly zoned and formed between two generations of diopside. The chemical composition of the vesuvianite whiskers is more homogeneous and resembles that of the outermost rim of the vesuvianite needles. In the last stage, fluorapophyllite, prehnite, titanite, calcite and quartz overgrew vesuvianite. Whiskers of vesuvianite crystallized at low activity of CO 2 and P-T conditions corresponding to the prehnitepumpellyite facies. Single-crystal X-ray refinements of the structure of three vesuvianite whiskers, for which electron-microprobe data also were collected, revealed P4/nnc space-group symmetry and (F, Cl) substitution at O(10) within disordered strings running parallel to the four-fold axis. In addition, there is partial substitution of F at O(11), usually occupied by OH in lowtemperature vesuvianite. The high symmetry (P4/nnc) in low-temperature (<350°C) whiskers of vesuvianite adds evidence that the degree of string order is determined not only by the temperature of crystallization, as hitherto assumed, but also by the prevailing composition of the fluid and the regime of crystal growth leading to substitutions that disturb intra-rod order and particularly long-range rod order. Long-range rod order leads to reduced symmetry (P4/n or P4nc), typical of vesuvianite crystallized at low temperature in rodingites. Vesuvianite whiskers formed in a kinetic regime where the growth rates were selectively influenced by surface-active substances poisoning the prism faces. Growth of faces in vesuvianite whiskers is explained by a tangential layer-by-layer mechanism without participation of a central screw dislocation.Keywords: low-temperature vesuvianite, whisker, fluorine, composition, crystal structure, crystal growth, infrared spectra, Yakutia, Russia. SOMMAIRENous avons découvert des trichites et des aiguilles de vésuvianite riche en fluor avec diopside dans des cavités d'un skarn magnésien altéré dans les montagnes Tas-Khayakhtakh, en Yakoutie polaire, en Russie. Les cristaux aciculaires sont fortement zonés et se sont formés entre deux générations de diopside. La composition chimique de la vésuvianite trichitique est plus homogène, et ressemble à celle de la bordure des aiguilles de vésuvianite. Au stade ultime de croissance, fluorapophyllite, prehnite, titanite, calcite et quartz ont englobé la vésuvianite. Les trichites de vésuvianite ont cristallisé à une faible activité de CO 2 à des conditions de P et de T correspondant au faciès prehnite-pumpellyite. Des affinements de la structure par diffraction X sur trois monocristaux trichitiques, pour lesquels nous possédons des données sur la composition obtenues par analyses à la microsonde § (11), où loge normalement un groupe OH dans la vésuvianite de basse température. La symétrie élevée (P4/nnc) des trichites formées à faible température (<350°C) vie...

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Section: Conditions Of Growth and Mechanism Of Formation Of The Vesuvmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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MORPHOLOGY, COMPOSITION AND STRUCTURE OF LOW-TEMPERATURE P4/nnc HIGH-FLUORINE VESUVIANITE WHISKERS FROM POLAR YAKUTIA, RUSSIA

Galuskin

Armbruster

Malsy

et al. 2003

The Canadian Mineralogist

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“…In the first volume, he reported that the original tourmaline deposits were depleted, and that Anjanabonoina was the only deposit being mined for tourmaline. He illustrated the common crystallographic forms of this tourmaline (figure 4; see also Goldschmidt, 1923), and noted that particularly large and beautiful crystals were found in the eluvial workings there. Detailed descriptions of the color zoning and corresponding physical properties in Madagascar tourmaline (including crystals from Anjanabonoina) also were provided.…”

Section: Figure 1 These Slices Of Tourmaline From Anjanabonoina Werementioning

confidence: 98%

Liddicoatite Tourmaline From Anjanabonoina, Madagascar

Dirlam¹,

Laurs²,

Pezzotta³

et al. 2002

Gems & Gemology

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“…In the 20 th Century, Goldschmidt (1888Goldschmidt ( -1947 interpreted this statement as "the primary basis of crystal chemistry" (Goldschmidt, 1937). The thesis of Häuy combined with Steno's law is the crystallographic analogue of the Proust's generalization in chemistry.…”

Section: Metzger It Her Doctoral Dissertation Genèse De La Science Dmentioning

confidence: 99%