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1.
A materials failure relation of accelerating creep as empirical description of damage accumulation 总被引：1，自引：0，他引：1
A general materials failure relation,
, describes accelerating creep of materials with rate coefficients andA, by relating rates of deformation,
, to changes in deformation rate,
(Voight, 1988). Time of failure can be extrapolated from inverse rate versus time data, and andA may be derived to permit one to calculate the failure time. The method is of value for quantitative hazard assessments.Mechanisms leading to damage accumulation during accelerating creep include creep fracture by stress corrosion and power law lattice deformation. These mechanisms are examined here as phenomenologically related to the materials failure relation. Apparently, both mechanisms favour , where is the parameter of the materials failure relation controlling the sensitivity to accelerating activity. For pure shear governed by power law creep of powerp, under constant load, =2.0 andA=p. Stress corrosion is widely described by Charles' equation, relating crack velocity to stress intensity during subcritical crack growth by the stress corrosion indexn. The relationship betweenn and is given by =(2n–2)/n. 相似文献
2.
Zusammenfassung Colquiriit tritt in Vergesellschaftung mit Ralstonit, Gearksutit, Zinkblende, Madocit und Pyrit im Bereich der Zinnlagerstätte von Colquiri in Bolivien auf. Das als selten zu betrachtende Mineral bildet maximal cm-große xenomorphe durchscheinende bis durch-sichtige Körner von weißlicher Farbe. Es zeigt keine Spaltbarkeit. Härte ca. 4; Dichte (gem.) 2,94, (ber.) 2,95 g/cm3;n
1,385±0.002,n
1,388±0,002, einachsig oder schwach zweiachsig, negativ. Colquiriit kristallisiert trigonal, Raumgruppe
oderP31c,a
0 5,02,c
0 9,67 Å,Z=2. Stärkste Linien des Pulverdiagramms: 3,98(7)
; 3,23(10)
; 2,22(9)
; 1,736(8)
. Eine chemische Analyse ergab: Li 3,1, Na 0,34, Mg 0,55, Ca 22,8, Al 13,4, F 58,0, Gewichtsverlust (105 °C) 0,5, Summe 98,69%, woraus sich die idealisierte Formel LiCaAlF6 ableiten läßt. Beim Erhitzen wird das Gitter zwischen 800 und 900°C zerstört.
Colquiriite, a new fluoride mineral from the Colquiri tin deposit in Bolivia
Summary Colquiriite occurs at the Colquiri tin deposit in Bolivia and is associated with ralstonite, gearksutite, sphalerite, madocite and pyrite. The mineral, which probably is a rare species, forms anhedral translucent to transparent white grains reaching up to 1 cm in size. No cleavage; hardness about 4; density (meas.) 2.94, density (calc.) 2.95 g/cm3;n 1.385±0.002,n 1.388±0.002, uniaxial or weakly biaxial, negative. Colquiriite is trigonal,a 0 5.02,c 0 9.67 Å, space group orP31c,Z=2. The strongest lines of the powder pattern are: 3.98(7) ; 3.23(10) ; 2.22(9) ; 1.736(8) . The chemical analysis gave: Li 3.1, Na 0.34, Mg 0.55, Ca 22.8, Al 13.4, F 58.0, weight loss (105 °C) 0.5, sum 98.69%, leading to the idealized formula LiCaAlF6. Heating experiments show that the lattice breaks down between 800 and 900 °C. The new mineral and its name have been approved by the I.M.A. Commission on New Minerals and Mineral Names.相似文献
3.
Zusammenfassung Die chemische Analyse des neuen Minerals Johillerit mit der Elektronenmikrosonde ergab: Na2O 5,4, MgO 18,3, ZnO 5,4, CuO 15,8 und As2O5 55,8, Summe 100.7%. Aus diesem Ergebnis wurde die idealisierte Formel Na(Mg, Zn)3 Cu(AsO4)3 abgeleitet. Johillerit ist monoklin mit der RaumgruppeC2/c. Die Gitterkonstanten sind:a=11,870 (3),b=12,755 (3),c=6,770 (2) , =113,42 (2)°,Z=4. Die stärksten Linien des Pulverdiagramms sind: 4,06 (5) (22
), 3,50 (4) (310), 3,25 (8) (11
), 2,75 (10) (330, 240), 2,64 (5) (311, 13
, 40
), 1,952 (4) (13
, 35
), 1,682 (4) (20
, 460), 1,660 (5) (40
, 71
, 550, 64
), 1,522 (4) (442, 153, 13
). Es bestehen enge strukturelle Beziehungen zwischen Johillerit und O'Danielit, Na(Zn, Mg)3H2(AsO4)3, sowie einigen synthetischen. Verbindungen.Johillerit ist violett durchscheinend. Die Spaltbarkeit nach {010} ist ausgezeichnet und nach {100} und {001} gut.H (Mohs)3.D=4,15 undD
X
=4,21 g·cm–3. Das Mineral ist optisch zweiachsig positiv, 2V80 (5)°. Die Werte der Lichtbrechung sindn
=1,715 (4),n
=1,743 (4) undn
=1,783 (4). Die Auslöschung istn
b und auf (010)n
c16°. Johillerit ist stark pleochroitisch mit den AchsenfarbenX=violett-rot,Y = blauviolett undZ = grünblau. Das neue Mineral kommt in radialstrahligen Massen gemeinsam mit kupferhaltigem Adamin und Konichalcit in zersetzem Kupfererz von Tsumeb, Namibia, vor. Die Benennung erfolgte nach Prof. Dr.J.-E. Hiller (1911–1972).
Mit 1 Abbildung 相似文献
Johillerite, Na(Mg, Zn) 3 Cu(AsO 4 ) 3 , a new mineral from Tsumeb, Namibia
Summary Electron microprobe analysis of the new mineral johillerite gave Na2O 5.4, MgO 18.3, ZnO 5.4, CuO 15.8, and As2O5 55.8, total 100.7%. From this result, the ideal formula is given as Na(Mg, Zn)3 Cu(AsO4)3. Johillerite crystallizes monoclinic,C2/c. The unit cell dimensions are:a=11.870(3),b=12.755 (3),c=6.770 (2) , =113.42 (2)°,Z=4. The strongest lines on the X-ray powder diffraction pattern are: 4,06 (5) (22 ), 3,50 (4) (310), 3,25 (8) (11 ), 2,75 (10) (330, 240), 2,64 (5) (311, 13 , 40 ), 1,952 (4) (13 , 35 ), 1,682 (4) (20 , 460), 1,660 (5) (40 , 71 , 550, 64 ), 1,522 (4) (442, 153, 13 ). There is a close relationship between johillerite, o'danielite, Na(Zn, Mg)3H2(AsO4)3, and some synthetic compounds. Johillerite is violet in colour, transparent. Cleavage is {010} perfect, {100} and {001} good.H (Mohs)3.D=4.15 andD X =4.21 g·cm–3. The mineral is optically biaxial positive, 2V80 (5)°. The refractive indices are:n =1.715 (4),n =1.743 (4),n =1.783 (4). The extinction isn b and on (010)n c16°. Strongly pleochroic with axial coloursX=violet-red,Y=bluish violet andZ=greenish blue. The new mineral was found in radiated masses together with cuprian adamite and conichalcite in an oxidized copper ore from Tsumeb, Namibia. It is named in honour of Prof. Dr.J.-E. Hiller (1911–1972).
Mit 1 Abbildung 相似文献
4.
Chang-Jo F. Chung 《Mathematical Geology》1993,25(7):851-865
Multivariate statistical analyses have been extensively applied to geochemical measurements to analyze and aid interpretation of the data. Estimation of the covariance matrix of multivariate observations is the first task in multivariate analysis. However, geochemical data for the rare elements, especially Ag, Au, and platinum-group elements, usually contain observations the below detection limits. In particular, Instrumental Neutron Activation Analysis (INAA) for the rare elements produces multilevel and possibly extremely high detection limits depending on the sample weight. Traditionally, in applying multivariate analysis to such incomplete data, the observations below detection limits are first substituted, for example, each observation below the detection limit is replaced by a certain percentage of that limit, and then the standard statistical computer packages or techniques are used to obtain the analysis of the data. If a number of samples with observations below detection limits is small, or the detection limits are relatively near zero, the results may be reasonable and most geological interpretations or conclusions are probably valid. In this paper, a new method is proposed to estimate the covariance matrix from a dataset containing observations below multilevel detection limits by using the marginal maximum likelihood estimation (MMLE) method. For each pair of variables, sayY andZ whose observations containing below detection limits, the proposed method consists of three steps: (i) for each variable separately obtaining the marginal MLE for the means and the variances,
,
,
, and
forY andZ: (ii) defining new variables by
and
and lettingA=C+D andB=C–D, and obtaining MLE for variances,
and
forA andB; (iii) estimating the correlation coefficient YZ by
and the covariance
YZ
by
. The procedure is illustrated by using a precious metal geochemical data set from the Fox River Sill, Manitoba, Canada. 相似文献
5.
Cristobalite, a high temperature phase of silica, SiO2, undergoes a (metastable) first-order phase transition from a cubic,
, to a tetragonal, P43212 (or P41212), structure at around 220° C. The cubic C9-type structure for -cristobalite (Wyckoff 1925) is improbable because of two stereochemically unfavorable features: a 180° Si-O-Si angle and an Si-O bond length of 1.54 Å, whereas the corresponding values in tetragonal -cristobalite are 146° and 1.609 Å respectively. The structure of the -phase is still controversial. To resolve this problem, a symmetry analysis of the
(or P41212) transition in cristobalite has been carried out based on the Landau formalism and projection operator methods. The starting point is the ideal cubic (
) C9-type structure with the unit cell dimension a (7.432 Å) slightly larger than the known a dimension (7.195 Å at 205° C) of -cristobalite, such that the Si-O-Si angle is still 180°, but the Si-O bond length is 1.609 Å. The six-component order parameter driving the phase transition transforms according to the X4 representation. The transition mechanism essentially involves a simultaneous translation and rotation of the silicate tetrahedra coupled along 110. A Landau free-energy expression is given as well as a listing of the three types of domains expected in -cristobalite from the transition. These domains are: (i) transformation twins from a loss of 3-fold axes, (ii) enantiomorphous twins from a loss of the inversion center, and (iii) antiphase domains from a loss of translation vectors 1/2 110 (FP). These domains are macroscopic and static in -cristobalite, and microscopic and dynamic in -cristobalite. The order parameter , couples with the strain components as 2, which initiates the structural fluctuations, thereby causing the domain configurations to dynamically interchange in the -phase. Hence, the - cristobalite transition is a fluctuation-induced first-order transition and the -phase is a dynamic average of -type domains. 相似文献
6.
Laurence P. Aldridge James Finch Graeme J. Gainsford Kevin H. Patterson W. Craighead Tennant 《Physics and Chemistry of Minerals》1991,17(7):583-590
Electric field gradient (EFG) measurements for Fe2+ in the cis- and trans-sites of a large single crystal of trioctahedral biotite of the lM polytype are described. Attempts to apply thickness and polarisation corrections are outlined. The measured EFG's are distinctly rhombic: = 0.28 and 0.42 respectively for the cis- and transsites and the EFG principal directions lie approximately along the crystallographic axes. For the cis-site V
y
lies close to the normal to the basal plane while for the transsite
lies close to this direction. 相似文献
7.
Richard J. Lisle 《International Journal of Earth Sciences》1985,74(3):657-663
Twenty-eight quartz c-axis fabrics from individual pebbles from a single outcrop of deformed conglomerate have been measured. These pebbles vary in composition and have undergone different amounts of strain. Contrary to expectations based on published results of computer simulated deformation by intracrystalline slip of pure quartzites, it is observed that fabrics are not stronger in the more highly deformed pebbles. Instead, the fabric strength is related to the quartz content of the pebbles. Pure quartzites show the strongest fabrics. As the percentage of non-quartz minerals increases up to 25% the strength of the fabrics rapidly decreases, though the influence of composition becomes less marked when impurities exceed 25%. These observations can be explained if the deformation of the impure quartzites included a contribution from a non-intracrystalline mechanism such as grain boundary sliding.
Zusammenfassung Von einem einzelnen Aufschluß eines deformierten Konglomerates wurden 28 Quarz c-Achsen Gefügebilder aufgenommen, jeweils von verschiedenen Geröllen. Diese Gerölle unterschieden sich in ihrer Zusammensetzung sowie in ihrem Deformationsgrad. Im Gegensatz zu den Erwartungen, basierend auf veröffentlichten Computersimulationen von intrakristallinen Gleitungen in reinem Quarzit, wurde beobachtet, daß die Gefüge von stark deformierten Kieseln nicht entsprechend stärker ausgeprägt sind, sondern, das Gefüge ist abhängig vom jeweiligen Quarzgehalt der Kiesel: reiner Quarzit zeigt das ausgeprägteste Gefüge. Wenn aber die Fremdanteile bis zu 25% betragen, verringert sich die Stärke der Gefügeausrichtung. Dieser Einfluß geht jedoch erneut zurück, sobald der Fremdanteil 25% übersteigt. Diese Beobachtungen können erklärt werden, wenn die Deformation des unreinen Quarzites auch mit nicht intrakristallin bezogenen Mechanismen im Zusammenhang steht, zum Beispiel mit Gleitungen an Korngrenzen.
Résumé Vingt-huit mesures de fabriques d'axes c de quartz ont été effectuées dans des cailloux différents provenant d'une même affleurement de conglomérat déformé. Ces cailloux varient en composition et ont été déformés à des degrés divers. Contrairement à ce que laissent prévoir les résultats publiés de la simulation par ordinateur de déformations par glissement intracristallin dans des quartzites purs, on constate que les fabriques ne sont pas plus orientées dans les cailloux les plus déformés. En effet, l'intensité de la fabrique est en relation avec la teneur en quartz des cailloux. Les quartzites purs montrent les fabriques les mieux exprimées. Lorsque la proportion des minéraux autres que le quartz augmente jusque 25%, l'orientation de la fabrique décroît rapidement, tandis qu'au-delà de 25%, l'influence de la composition se marque moins. On peut interpréter ces observations en admettant que dans la déformation des quartzites impurs, intervient un mécanisme non intracristallin, tel qu'un glissement le long des surfaces des grains.
, . , , . , : , , : . 25%, . , 25%, . , , , .: .相似文献
8.
Fractionation of yttrium (Y) and the rare earth elements (REEs) begins in riverine systems and continues in estuaries and the ocean. Models of yttrium and rare earth (YREE) distributions in seawater must therefore consider the fractionation of these elements in both marine and riverine systems. In this work we develop a coupled riverine/marine fractionation model for dissolved rare earths and yttrium, and apply this model to calculations of marine YREE fractionation for a simple two-box (riverine/marine) geochemical system. Shale-normalized YREE concentrations in seawater can be expressed in terms of fractionation factors (
ij
) appropriate to riverine environments (
) and seawater (
):
where
and
are input-normalized total metal concentrations in seawater and
is the ratio of total dissolved Y in riverwater before
and after
commencement of riverine metal scavenging processes. The fractionation factors (
ij
) are calculated relative to the reference element, yttrium, and reflect a balance between solution and surface complexation of the rare earths and yttrium. 相似文献
9.
Dr P. Keller Prof. Dr. H. Hess Dr. P. Süsse Dr. G. Schnorrer P. J. Dunn 《Mineralogy and Petrology》1979,26(1-2):51-58
Zusammenfassung Das neue Mineral Koritnigit ist ein wasserhaltiges Zinkhydrogenarsenat der Formel Zn[H2O|HOAsO3]. Die chemische Analyse (Elektronenmikrosonde und T.G.A.) ergab: As2O5 51,75%, ZnO 35,97% und H2O 12,3%, Summe 100,0%. Die HOAsO3-Ionen wurden IR-spektroskopisch nachgewiesen. Koritnigit ist löslich in kalter, verdünnter HCl und HNO3.Die Gitterkonstanten sind:a
0=7,948(2),b
0=15,829(5),c
0=6,668(2) Å, =90,86(2), =96,56(2), =90,05(2)o,V=833,2(4)Å3,V=8. Die Raumgruppe ist
. Die stärksten Linien des Pulverdiagramms sind: 7,90(10) (020,100), 3,83(7) (
), 3,16(9) (
) 2,926(4) (150), 2,679(4) (
), 2,461(6) (
), 2,186(5) (
), 1,969(4) (400), 1,649(3) (004).Koritnigit ist wasserklar bis durchscheinend weiß. Idiomorphe Kristalle sind nicht bekannt. Die Spaltbarkeit nach {010} ist ausgezeichnet und auf {010} sind Spaltspuren nach [001] und nach [100] erkennbar. Härte 2.G=3,54 g·cm–3,D
x
=3,56 g·cm–3. Koritnigit ist optisch zweiachsig positiv, 2V70(5)o. Die Werte der Lichtbrechung sind:n
=1,632(5),n
=1,652(3) undn
=1,693(3).Koritnigit wurde auf der 31. Sohle der Tsumeb-Mine, Südwestafrika gefunden. Er kommt als Sekundärmineral in Paragenese mit Cu-Adamin, Stranskiit und drei weiteren, vorerst nicht identifizierten mineralen in Zersetzungshohlräumen von Tennantit vor.
Mit 2 Abbildungen
Herrn Univ. Prof. Dr.H. Meixner zum 70. Geburtstag gewidmet. 相似文献
Koritnigite, Zn[H2O|HOAsO3], a new mineral from Tsumeb, South West Africa
Summary The new mineral koritnigite is a hydrated zinc hydrogen arsenate with the formula Zn[H2O|HOAsO3]. Chemical analysis (electron microprobe and t.g.a.) gave: As2O5 51.75%, ZnO 35.97%, and H2O 12.3%, total 100.0%. The HOAsO3 ions were determined by IR spectroscopy. Koritnigite is soluble in cold diluted HCl and HNO3. The unit cell dimensions are:a 0=7.948(2),b 0=15.829(5),c 0=6.668(2)Å, =90.86(2), =96.56(2), =90.05(2)o,V=833.2(4) Å3,Z=8. The space group is . The strongest lines of the powder pattern are: 7.90(10) (020, 100), 3.83(7) ( ), 3.16(9) ( ), 2.926(4) (150), 2.679(4) ( ), 2.461(6) ( ), 2.186(5) ( ), 1.969(4)(400), 1.649(3) (004).
Mit 2 Abbildungen
Herrn Univ. Prof. Dr.H. Meixner zum 70. Geburtstag gewidmet. 相似文献
10.
To investigate high-temperature creep and kinetic decomposition of nickel orthosilicate (Ni2SiO4), aggregates containing 3 vol% amorphous SiO2 have been deformed in uniaxial compression at a total pressure of one atomsphere. Twenty-three samples with grain sizes (d) from 9 to 30 m were deformed at temperatures (T) from 1573 to 1813 K, differential stresses () from 3 to 20 MPa, and oxygen fugacities (f
o
2) from 10-1 to 105 Pa. At temperatures up to 1773 K, the steady-state creep rate () can be described by the flow law
|
相似文献
11.
Single crystal Raman spectra of pyrite-type RuS2, RuSe2, OsS2, OsSe2, PtP2, and PtAs2 are presented and discussed with reference to the energies of the X-X stretching modes
x-x (A
g, F
g) and the X2 librations
(E, 2Fg). The main results obtained are (i) strong Raman resonance effects, (ii) different sequences for
x-x (A
g) and
(E
g), i.e.,
R_{x_2 } $$
" align="middle" border="0">
for PtP2 and PtAs2 and
R_{x_2 } $$
" align="middle" border="0">
for OsS2, owing to the interplay of intraionic and interionic lattice forces, (iii) greater strengths for the intraionic P-P and As-As bonds compared to the S-S and Se-Se bonds, respectively, and (iv) a strong influegnce of the metal ions on the strength of the X-X bonds.This is contribution LXI of a series of papers on lattice vibration spectra 相似文献
12.
Titania, TiO2, precipitation in natural blue sapphire (Fe, Ti: -Al2O3) has been investigated using high resolution and analytical transmission electron microscopy. The structure and habit of the TiO2 precipitate depends on both the Ti4+ concentration and the temperature at which the precipitate formed. Tetragonal TiO2 (Rutile) grows at 1350° C but at 1150° C an orthorhombic non-equilibrium TiO2 polymorph precipitates. Both TiO2 polymorphs nucleate in the (0001)s plane as lens shaped discs twinned along their diameter. The crystallographic alignment of each type of TiO2 precipitate with respect to the -Al2O3 host matrix provides a high degree of structural coherency with minimal lattice mismatch. Electron diffraction analysis established the following precipitate/host orientation relationships: tetragonal TiO2: {011}r {11
07B;100}r(0001)s and 01
r10
0s twinned along the (011)r planeand orthorhombic TiO2: {021}{11
0}s, {100}(0001)s and 0
2 10
0s twinned along the (021) plane. 相似文献
13.
The junctions of cracks in mudcrack, patterned ground, and columnar joint patterns can be categorized into Y, T,and Xtypes. The mean number of sides,
,to the polygonal areas in such nets is
= 2(2JT + 3JY + 4JX)/(JT + JY + 2JX)where JT, JY,and JX
are the proportions of T, Y,and Xjunctions, respectively. 相似文献
14.
Prof. L. Fanfani Prof. P. F. Zanazzi Dr. Anna Rosa Zanzari 《Mineralogy and Petrology》1977,24(3):169-178
Summary The crystallography of roscherite is more complicated than previously thought. Single crystal X-ray work on material from Foote Mine (California) gave triclinic symmetry. The unit cell corresponding to the one adopted for monoclinic roscherite hasa=15.921,b=11.965,c=6.741 Å, =91°04, =94°21, =89°59 1/2, space group
. The least-squares refinement of the structure using 2380 non zero reflections with anisotropic temperature factors resulted in a conventional reliability factorR=0.060.The X-ray study indicates the formula
while that proposed for monoclinic roscherite is
The atomic arrangements of both varieties of roscherite are very similar. The lowering of symmetry is caused by the segregation of the trivalent cations into only half of the sites of a monoclinic point position. Crystallochemical considerations suggest that the symmetry of roscherite does not depend on the kind of trivalent cations occupying the 6-coordinated position, but rather by the ratio between trivalent and divalent metal ions.
Die Kristallstruktur eines triklinen Roscherites Zusammenfassung Die Kristallographie des Roscherites ist komplizierter als man bisher annahm. Einkristall-Röntgenuntersuchungen an Material von Foote Mine (Kalifornien) ergaben trikline Symmetrie. Die Elementarzelle, welche der für monoklinen Roscherit angenommenen entspricht, hata=15,921,b=11,965,c=6,741 Å, =91°04, =94°21, =89°59 1/2, Raumgruppe . Die Verfeinerung der Struktur mit der Methode der kleinsten Quadrate ergab unter Verwendung anisotroper Temperaturfaktoren für 2380 beobachtete Reflexe einen konventionellen ZuverlässigkeitsindexR=0,060.Die Röntgenuntersuchung weist auf die Formel , während für monoklinen Roscherit vorgeschlagen wurde. Die Atomanordnungen beider Abarten des Roscherites sind sehr ähnlich. die Symmetrieerniedrigung wird dadurch hervorgerufen, daß die dreiwertigen Kationen nur die Hälfte der Positionen einer monoklinen Punktlage besetzen. Kristallchemische Überlegungen weisen darauf hin, daß die Symmetrie nicht von der Art der dreiwertigen Kationen, welche eine 6-koordinierte Punktlage besetzen, abhängt, sondern vielmehr von dem Mengenverhältnis zwischen 3-wertigen und 2-wertigen Metallionen. With 1 Figure 相似文献 15.
Water in microcrystalline quartz of volcanic origin: Agates 总被引：2，自引：0，他引：2
O. W. Flörke B. Köhler-Herbertz K. Langer I. Tönges 《Contributions to Mineralogy and Petrology》1982,80(4):324-333
Agates of volcanic origin, containing the different quartz species, fibrous, length-fast chalcedony (CH), granular fine quartz (FQ), and fibrous, length-slow, to lepidospheric quartzine (QN), have been investigated to evaluate possible relations between microstructure, i.e. crystallite size and texture, refractive indices, densities, contents of trace elements and of water, as well as dehydration behaviour. By means of near infrared spectroscopy, total water contents
, could be differentiated quantitatively into contents of molecular water,
, and silanole-group water,
. Despite the low total water contents of the agates studied (
between 1 and 2 wt.%), near infrared spectroscopy results in reliable data on
and
.Wall-layering CH consists of fibrous quartz crystals and exhibits higher C-ratios,
, than horizontally layered FQ which consists predominantly of granular quartz crystals (C
CH=0.45±0.11 (N=6), C
FQ=0.36±0.10 (N=4). This result is interpreted to be due to analogy with the behaviour of C-ratios in fluid phase-deposited opals-AN (hyalithe) and liquid phase-deposited opals-AG (non-crystalline opal) or -CT (common opal) (Langer and Flörke 1974).Translucent layers of CH show mostly lower refractive indices, when measured parallel than when measured perpendicular to the axes of the quartz fibers. The same is true for milky layers of CH. Crystallite sizes are smaller in the latter than in the former.For all samples studied, exists a positive correlation between at% (1/2Ca+1/2Mg+Na+K+Li) and at% (Al3++Fe3+). This indicates that at least parts of (A13++ Fe3+) substitute for Si in the quartz structure. The charge is balanced by incorporation of di- and mono-valent cations in structural interstices. When the quantity at % H+, as obtained from
, is included into the sum at% (1/2 Me2++Me+), the above correlation is destroyed. This result could be indicative for a strong concentration of the Si-OH groups in the surface of the quartz microcrystallites. 相似文献
16.
Prof. Dr. K. Walenta 《Mineralogy and Petrology》1977,24(3):125-132
Zusammenfassung Machatschkiit ist ein neues wasserhaltiges Calciumarsenat, das in der Grube Anton bei Schiltach im mittleren Schwarzwald (BRD) 1960 gefunden wurde. Es kommt zusammen mit Gips, Pharmakolith, Pikropharmakolith und Sainfeldit als Sekundärbildung krustenförmig auf Granit vor.Als charakteristische Form tritt das Rhomboeder
auf. Keine Spaltbarkeit, Bruch muschelig, Härte 2–3,G=2,5 bis 2,6 g·cm–3,D
x
=2,50 g·cm–3, farblos, durchsichtig bis durchscheinend. Optische Daten:n
=1,585±0,002,n
=1,593±0,002, einachsig oder schwach zweiachsig, negativ.Gitterkonstanten:a
0=15,10,c
0=22,59 Å,a
0c
0=11,4960,Z=12;a
rh
=11,52 Å, =81°52,Z=4. Mögliche Raumgruppen:R32,R3m,
. Stärkste Linien des Pulverdiagramms: 8,59 (10)
(110), 5,34 (8)
(210), 3,59 (8)
. Eine chemische Analyse ergab nach Umrechnung folgende Zusammensetzung: CaO 29,5%, As2O5 40,8%, SO3 0,5%, H2O 29,2%, Summe 100,0%. Dies kommt der Formel Ca3(AsO4)2 · 9 H2O sehr nahe. In verdünnter HCl und HNO3 ist der Machatschkiit leicht löslich.
Machatschkiite, a new arsenate mineral from the Anton Mine in the Heubach valley near Schiltach (Black Forest, Federal Republic of Germany) Summary Machatschkiite is a new hydrous calcium arsenate which was found 1960 in the Anton Mine near Schiltach in the central Black Forest. It is a secondary mineral which occurs in crusts on granite in association with gypsum, pharmacolite, picropharmacolite and sainfeldite.The characteristic form is the rhombohedron . No cleavage, fracture conchoidal, hardness 2–3,G=2.5–2.6 g·cm–3,D x =2.50 g·cm–3, colourless, transparent to translucent. Optical data:n =1.585±0.002,n =1.593±0.002, uniaxial or weakly biaxial, negative.Unit-cell dimensions:a 0=15.10,c 0=22.59 Å,a 0c 0=11.4960,Z=12;a rh =11.52 Å, =81°52,Z=4. Possible space groups:R32,R3m, . Strongest lines of the powder pattern: 8.59 (10) (110), 5.34 (8) (210), 3.59 (8) . A chemical analysis gave the following composition after recalculation: CaO 29.5%, As2O5 40.8%, SO3 0.5%, H2O 29.2%, total 100.0%. This agrees well with the formula Ca3(AsO4)2 · 9 H2O. Machatschkiite is easily soluble in diluted HCl and HNO3. Mit 3 Abbildungen 相似文献 17.
An internal variable model for the creep of rocksalt 总被引：3，自引：0，他引：3
Summary The creep strain rate
of rocksalt, like that of other ductile crystalline materials, can be described by a power law equation of the type
(
)
n
, where the active stress
is the difference between the total deviatoric applied stress and an internal stress
i
. In this paper, the origin and the nature of this internal stress, which develops during inelastic deformation of the material, are discussed. It is shown that this internal stress can serve as an internal (or state) variable in the constitutive model of rocksalt, which reflects the microstructure evolution of the material under the competitive action of hardening and recovery mechanisms.An analysis of experimental data, both our own and those taken from the literature, demonstrates that such a law is able to correctly reproduce rocksalt creep test results in the steady-state domain. The proposed model is in accordance with the macroscopic and microscopic behavior of salt, and with direct measurements of the internal stresses made by others on this material. 相似文献
18.
To investigate the point defect chemistry and the kinetic properties of manganese olivine Mn2SiO4, electrical conductivity () of single crystals was measured along either the [100] or the [010] direction. The experiments were carried out at temperatures T=850–1200 °C and oxygen fugacities
atm under both Mn oxide (MO) buffered and MnSiO3 (MS) buffered conditions. Under the same thermodynamic conditions, charge transport along [100] is 2.5–3.0 times faster than along [010]. At high oxygen fugacities, the electrical conductivity of samples buffered against MS is 1.6 times larger than that of samples buffered against MO; while at low oxygen fugacities, the electrical conductivity is nearly identical for the two buffer cases. The dependencies of electrical conductivity on oxygen fugacity and temperature are essentially the same for conduction along the [100] and [010] directions, as well as for samples coexisting with a solid-state buffer of either MO or MS. Hence, it is proposed that the same conduction mechanisms operate for samples of either orientation in contact with either solid-state buffer.The electrical conductivity data lie on concave upward curves on a log-log plot of vs
, giving rise to two
regimes with different oxygen fugacity exponents. In the low-
regime
, the
exponent, m, is 0, the MnSiO3-activity exponent, q, is 0, and the activation energy, Q, is 45 kJ/mol. In the high
regime
10^{ - 7} {\text{atm}}} \right)$$
" align="middle" border="0">
, m=1/6, q=1/4–1/3, and Q=45 and 200 kJ/mol for T<1100 °c=" and=">T>1100 °C, respectively. 相似文献
19.
The partition of Ni between olivine and monosulfide-oxide liquid has been investigated at 1300–1395° C,
=10–8-9–10–6.8, and
=10–2.0–10–0.9, over the composition range 20–79 mol. % NiS. The product olivine compositions varied from Fo98 to Fo59 and from 0.06 to 3.11 wt% NiO. The metal/sulfur ratio of the sulfide-oxide liquid increases with increase in
, decrease in
, and increase in NiS content. The Ni/Fe exchange reaction has been perfectly reversed using natural olivine and pure forsterite as starting materials. The FeO and NiO contents of olivine from runs equilibrated at the same
and
form isobaric distributions with NiS content, which, to a first approximation, are dependent at constant temperature and total pressure on a variable term, –0.5 log (
/
). The Ni/Fe distribution coefficient (K
D3) exhibits only a weak decrease from 35 to 29 with increase in
from the IW buffer to close to the FMQ buffer. At
values higher than FMQ, the sulfide-oxide liquid has the approximate composition (Ni,Fe)3±xS2K
D358. The present K
D3 vs O/(S+O) data define a trend which extrapolates to K
D320 at 10 wt% oxygen in the sulfide-oxide liquid. The compositions of olivine and Ni-Cu sulfides associated with early-magmatic basic rocks and komatiites are consistent, at 1400° C, with a value of -log (
/
) of about 7.7, which is equivalent to 0.0 wt% oxygen in the hypothesized immiscible sulfide-oxide liquid. Therefore, K
D3 would not be reduced significantly from the 30 to 35 range for sulfide-oxide liquids with low oxygen contents. 相似文献
20.
An experimental study of the diffusion of oxygen in quartz and albite using an overgrowth technique 总被引：1，自引：0，他引：1
S. C. Elphick P. F. Dennis C. M. Graham 《Contributions to Mineralogy and Petrology》1986,92(3):322-330
Diffusion rates of18O tracer in quartz ( c, 1 Kb H2O) and Amelia albite ( 001, 2 Kb H2O) have been measured, using Secondary Ion Mass Spectrometry (SIMS). A new technique involving hydrothermal deposition of labelled materials has removed the possibility of pressure solution-reprecipitation processes adversely affecting the experiments. Reported diffusion constants are:-quartz ( c),
,Q=98±7 KJ mol–1 (600–825° C, 1 Kb); Amelia albite ( 001),
,Q=85±7 KJ mol–1, (400–600° C, 2 Kb). Measured quartz18O diffusivities decrease discontinuously at the- transition, reflecting strong structural influences. The reported albite data agree with previously recorded studies, but-quartz data indicate significantly lower activation energies. Possible causes of this discrepancy, and some geological consequences, are noted. 相似文献
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