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  • 1985-1989  (13)
  • 1970-1974  (19)
  • 1965-1969  (13)
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  • 1
    Electronic Resource
    Electronic Resource
    Ein synthetisches Zwischenglied zwischen dioktaedrischen und trioktaedrischen Glimmern (1965)
    Springer
    Naturwissenschaften 52 (1965), S. 182-183 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00623240
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  • 2
    Electronic Resource
    Electronic Resource
    Synthetische Amphibole mit OH-Überschuß im System Na2O−MgO−SiO2−H2O (1969)
    Springer
    Naturwissenschaften 56 (1969), S. 414-415 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00593623
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  • 3
    Electronic Resource
    Electronic Resource
    High-pressure, high-temperature stability of surinamite in the system MgO-BeO-Al2O3-SiO2-H2O (1986)
    Springer
    Contributions to mineralogy and petrology 92 (1986), S. 113-127 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The MgAl surinamite end member, (Mg3Al3)[6]O[AlBeSi3O15], was synthesized in the requisite system with and without water. The new phase is monoclinic, space group P2/n, with a=9.881(1)Å; b=11.311(1) Å; c=9.593(1) Å; β=109.52(2)°. Refractive indices are n x=1.7015(20); n y=1.7035(20); n z=1.7055(20). The infrared spectrum shows characteristic differences against the structurally related and optically extremely similar phase sapphirine. Using the seeding technique, the preliminary stability field for MgAl surinamite was found to lie at high temperatures (≳650 °C) and high pressures (≳4 kbar). At lower temperatures breakdown takes place to hydrous assemblages of chlorite, talc, and chrysoberyl with kyanite or yoderite; at lower pressures chrysoberyl forms parageneses with sapphirine and cordierite. In crystal chemical terms the underlying principle for the stability of surinamite versus that of the low-pressure assemblages is the higher proportion of octahedrally coordinated Al in surinamite (75%). Following the same principle surinamite itself decomposes at still higher pressures to a paragenesis, in which all Al enters octahedral coordination (pyrope+a chrysoberyl-type phase and some unidentified X-ray peaks). The stability field of synthetic MgAl surinamite is in good agreement with P, T-estimates of some 8–12 kbar, 800°–950° C as taken from the literature for the few occurrences of natural, Fe-bearing surinamite in granulite and upper amphibolite facies environments. The incorporation of iron in surinamite must be limited, because this mineral is known to coexist with its more iron-rich breakdown assemblage almandine-rich garnet+chrysoberyl. As the minimum melting curve of granite under hydrous conditions lies outside the surinamite field up to a water pressure of about 20 kbar, the absence of surinamite in normal granitic pegmatites can already be explained by physical constraints. However, there are probably also chemical constraints in the generally high Fe/Mg bulk chemistry of the pegmatite environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00373969
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  • 4
    Electronic Resource
    Electronic Resource
    A miscibility gap in trioctahedral Mn-Mg-Fe chlorites: Evidence from the Lienne Valley manganese deposit, Ardennes, Belgium (1986)
    Springer
    Contributions to mineralogy and petrology 94 (1986), S. 333-342 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Low-temperature veinlets crosscutting low-grade manganiferous ironstones of Ordovician age contain four texturally distinct types of chlorites with nearly constant Al/Si-ratios that form two separate populations regarding their Mn/Mg/Fe-ratios: One with low iron contents (〈1.5 w.% FeO) and molar Mg/Mn-ratios just below unity (magnesian pennantites), the other with higher iron (7–11 w.% FeO) and Mg/Mn≳4 (manganoan clinochlores). The two populations, which can be distinguished readily by their characteristic optical elongation and dispersion colors, are intimately intergrown and have formed partly during consecutive stages of a chlorite crystallization sequence, partly by simultaneous growth and possibly even as exsolution products of a pre-existing homogeneous chlorite phase of intermediate composition. These findings indicate a miscibility gap in the chlorite solid solutions beginning along the binary Mg-Mn series and extending into the ternary system. There may be a solvus relationship with the miscibility gap closing at higher temperatures (400° C?). One very intensely colored chlorite type of the pennantite population may contain Fe3+ or Mn3+ or both. Additional minerals in the veinlets are spessartine, kutnahorite, quartz, and an allanite-piemontite phase. Crystallization began near the centers of the present veins with Mn-rich minerals and continued towards their edges and into the extremely thin ends of the developing fractures with the deposition of the more Fe-rich chlorites that are in equilibrium with the ironstone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371442
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  • 5
    Electronic Resource
    Electronic Resource
    Whiteschist, a new type of metamorphic rock formed at high pressures (1974)
    Springer
    International journal of earth sciences 63 (1974), S. 597-609 
    Details
    ISSN: 1437-3262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Abstract The association of talc with kyanite is defined to be the characteristic mineral assemblage of a new type of crystalline schist, named whiteschist, which has recently been found in several localities, partly even on a regional scale. Based on experimental evidence this assemblage appears at water pressures in excess of about 10 kilobars. Its compositional limitation to rocks rich in Mg and Al, but poor in Fe2+, Ca, and alkalies does not allow the introduction of a new facies of metamorphism. However these unusual rock compositions provide a sensitive geobarometer in the pressure range near 10 kb for which other more “normal” rock compositions do not seem to be critical.
    Abstract: Résumé On définit l'association du talc avec le disthène comme paragenèse minérale caracteristique d'un nouveau type de schiste crystallin, nommé schiste blanc, qu'on a trouvé récemment dans plusieurs localités, des fois même en distribution régionale. Des travaux experimentaux ont démontré que cette paragenèse apparaît aux pressions d'eau au-dessus de 10 kilobars à peu près. La limitation de cette paragenèse aux roches riches en Mg et Al, mais pauvres en Fe2+, Ca et en éléments alcalins ne permet pas l'introduction d'un facies nouveau de métamorphisme. Cependant ces compositions non usuelles des roches représentent un géobaromètre sensitif dans la région des pressions près de 10 kb, où il semble que d'autres compositions plus « normales » des rochcs ne donnent pas des indications critiques.
    Notes: Zusammenfassung Die Vergesellschaftung von Talk mit Disthen wird definiert als die charakteristische Mineralparagenese eines neuen Typs von Kristallinem Schiefer, genannt Weißschiefer, der neuerdings von mehreren Lokalitäten, zum Teil sogar in regionaler Verbreitung, bekannt wurde. Durch experimentelle Arbeiten ist erwiesen, daß diese Paragenese bei Wasserdrucken oberhalb von etwa 10 Kilobar auftritt. Die Beschränkung dieser Paragenese auf Gesteinszusammensetzungen, die reich an Mg und Al, aber arm an Fe2+, Ca und Alkalien sind, gestattet nicht die Einführung einer neuen Fazies der Metamorphose. Dennoch stellen diese ungewöhnlichen Gesteinszusammensetzungen ein empfindliches Geobarometer im Druckbereich um 10 kb dar, für den anscheinend andere, ‚'normalere“ Gesteinschemismen unkritisch sind.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01820834
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  • 6
    Electronic Resource
    Electronic Resource
    Die Möglichkeit der Entstehung ultrabasischer Magmen bei Gegenwart geringer Alkalimengen (1968)
    Springer
    International journal of earth sciences 57 (1968), S. 349-362 
    Details
    ISSN: 1437-3262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Abstract Mixtures of forsterite and enstatite show partial melting in the pressure range 1–5 kb at very low temperatures (approximately 550–700° C), if small amounts of K2O are added in the presence of excess H2O. Since alkalies and water are also expected to be minor constituents of the material forming the earth's mantle, they may cause, in this region, the formation of ultrabasic crystal mushes that may intrude into higher levels, i. e. the earth's crust. The presence of alkalies in ultrabasic melts before or during their emplacement may result in alkali metasomatism of the adjoining country rocks, because most of these alkalies are being incorporated at still lower temperatures in a gas phase leaving the intrusion.
    Abstract: Résumé On a trouvé qu'en présence de K2O et d'un excès d'eau des mélanges de forsterite et d'enstatite peuvent être fondues en partie à des températures très basses (550–700° C), sous une pression d'un à 5 kilobars. La présence des alkalis et de l'eau dans l'enveloppe pierreuse externe est probable. Conséquemment on pourrait supposer la formation de magmas d'ultrabasite par ces components dans l'enveloppe pierreuse externe. Ces magmas pourraient pénétrer dans des étages élevés. La présence des alkalis dans les magmas d'ultrabasite, avant et aussi bien au cours de la formation de ces dernières, pourrait se manifester par des métasomatoses d'alkali dans la roche encaissante, puisque à des températures encore plus basses les alkalis sont présents en phase volatile; cette phase peut quitter l'intrusion.
    Notes: Zusammenfassung Mischungen von Forsterit und Enstatit werden bei Zugabe von wenigen Prozent K2O in Anwesenheit eines Wasserüberschusses unter Drucken von 1 bis 5 Kilobar bereits bei sehr niedrigen Temperaturen (etwa 550–700° C) teilweise aufgeschmolzen. Da auch in den Gesteinen des Erdmantels die Gegenwart von Alkalien und Wasser zu erwarten ist, können diese Komponenten zur Bildung von Ultrabasit-Schmelzbreien im Oberen Erdmantel führen, welche in höhere Stockwerke, d. h. in die Erdkruste, intrudieren können. Die Anwesenheit von Alkalien in Ultrabasitschmelzen vor und während deren Platznahme kann sich durch Alkalimetasomatosen im Nebengestein äußern, da die Alkalien bei noch niedrigeren Temperaturen vorwiegend in eine leichtflüchtige Gasphase eingehen, welche die Intrusion verläßt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01821250
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  • 7
    Electronic Resource
    Electronic Resource
    Calcium-free pumpellyite, a new synthetic hydrous Mg–Al-silicate formed at high pressures (1986)
    [s.l.] : Nature Publishing Group
    Nature 321 (1986), S. 510-511 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] During a recent high-pressure investigation of the system MgO-Al2O3-SiO2-H2O (MASH) aimed at synthesizing a Ti-free ellenbergerite3, reflections were encountered in the powder X-ray diffraction pattern that did not fit any of the known crystalline phases of the MASH system, nor could they be ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/321510a0
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and stability of micas in the system K2O-MgO-SiO2-H2O and their relations to phlogopite (1971)
    Springer
    Contributions to mineralogy and petrology 30 (1971), S. 196-215 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A series of alumina-free micas was synthesized hydrothermally in the potassium-poor portion of the system K2O-MgO-SiO2-H2O. One end member of this series has the composition KMg2.5[Si4O10](OH)2, which, because of its octahedral occupancy, is intermediate between the dioctahedral and trioctahedral micas. From this end member a series of mica solid solutions extends towards more Mg-rich compositions. Single phase micas were obtained along the substitution line 2Mg for Si which appears to involve incorporation of part of the Mg in tetrahedral sites. It leads to a theoretical end member with a structural formula KMg3[Si3.5Mg0.5O10](OH)2. Solid solutions containing up to 75 mole % of this theoretical end member could be synthesized. The observed densities, water contents, and a one-dimensional Fourier synthesis are consistent with the assumed substitution. At 1 kb fluid pressure and 620° C the Si-rich end member KMg2.5[Si4O10](OH)2 decomposes to a more Mg-rich mica, the roedderite phase K2Mg5Si12O30, liquid, and H2O-rich vapor. With increasing Mg-content the thermal stability of the mica solid solutions increases up to 860°C at a composition of about K2O·6.2MgO·7.4SiO2·2H2O, i.e. KMg2.8[Si3.7Mg0.3O10](OH)2. This mica disintegrates directly into forsterite + liquid + H2O-rich vapor. The mica phase richest in Mg with a composition of about K2O·6.5MgO·7.25SiO2·2H2O, i.e. KMg2.875 [Si3.625Mg0.375O10](OH)2, breaks down at 765° C into forsterite, a more Si-rich mica, liquid, and H2O-rich vapor. This binary series of alumina-free micas forms a complete series of ternary solid solutions with normal phlogopite, KMg3[Si3AlO10](OH)2. Analyses of some natural phlogopites showing Si in excess of 3.0 (up to 3.18) per formula unit can be explained through this ternary miscibility range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00455671
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  • 9
    Electronic Resource
    Electronic Resource
    Lower temperature stability limit of Mg cordierite in the range 1–7 kb water pressure: A redetermination (1970)
    Springer
    Contributions to mineralogy and petrology 27 (1970), S. 225-238 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Hydrothermal experiments utilizing the seeding technique show conclusively that the lower temperature stability limit of Mg cordierite so far accepted (Schreyer and Yoder, 1964) represents metastable equilibria throughout the pressure range 1–7 kb. The stable equilibrium curve generally lies at somewhat higher temperatures and is not subdivided by an invariant point involving the phase pyrophyllite within this pressure range. Instead of pyrophyllite+andalusite+chlorite, hitherto assumed to be the breakdown assemblage of cordierite below 5 kb water pressure, the paragenesis Al silicate+chlorite+quartz was found to be stable over the entire pressure range investigated. The andalusite/kyanite transition, as determined by Richardson et al. (1969), is confirmed by a minor change of slope of the cordierite breakdown curve. Direct breakdown of cordierite into pyrophyllite-bearing assemblages must be limited to conditions below about 1 kb and 450° C. This gives indirect support to Kerrick's (1968) stability data on pyrophyllite, as opposed to those of Althaus (1969) and others. These new results offer an explanation for the common assemblage chlorite+andalusite (or kyanite)+quartz occuring in spotted slates, greenschists, and also as retrograde alteration products of natural cordierites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385779
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  • 10
    Electronic Resource
    Electronic Resource
    Stability of almandine in the system FeO-(Fe2O3)-Al2O3-SiO2-(H2O) at elevated pressures (1971)
    Springer
    Contributions to mineralogy and petrology 31 (1971), S. 132-144 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Almandine, although decomposing in the presence of metallic iron into the anhydrous subsolidus assemblage fayalite + ferrocordierite + hercynite solid solution at low pressures, melts incongruently to hercynitess + quartz + liquid at 10 kb. At pressures between about 12 and 20 kb the products of incongruent melting are hercynitess + liquid only, and at still higher pressures almandine melts congruently. For the intermediate pressures between 2 and 10 kb not investigated a sequence of probable breakdown and melting relations involving the phases ferrocordierite, fayalite, hercynitess, quartz, and liquid is derived through Schreinemakers' analyses. The lower temperature stability limit of almandine in the presence of water at low oxygen fugacities and pressures of 15 to 20 kb lies between 550° and 600° C as at low pressures. It is marked, however, by the breakdown to a hydrous assemblage involving chloritoid and the new phase aluminous deerite. Since the anhydrous melting at these pressures occurs between 1300° and 1400° C, the thermal stability range of almandine increases drastically with pressure. Its upper breakdown limit shows in principle a similar behavior as those of other garnet end members.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00373456
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