1-20 OF 47 RESULTS FOR

khmaralite

Results shown limited to content with bounding coordinates.
Follow your search
Access your saved searches in your account

Would you like to receive an alert when new items match your search?
Close Modal
Sort by
Journal Article
Published: 01 February 2009
American Mineralogist (2009) 94 (2-3): 270-282.
... configurational entropies for the simulations. The substantial SRO present is shown to reduce Sconfig by only 17–18%.Khmaralite is related to sapphirine but contains ca. 1.5 Be per 12 tetrahedra and shows different LRO of {Be, Al, Si}. The minority cation Be is concentrated in Q3 sites. If the exchange enthalpy...
FIGURES | View All (8)
Journal Article
Published: 01 February 2004
American Mineralogist (2004) 89 (2-3): 327-338.
... Be increases with P, following the MBeAS univariant reactions involving (sapphirine + surinamite + orthopyroxene + chrysoberyl + forsterite or spinel).Natural assemblages containing sapphirine and its Be-rich near-analog khmaralite from the Napier Complex, Enderby Land, East Antarctica formed at higher T (900...
FIGURES | View All (12)
Journal Article
Published: 01 August 2002
American Mineralogist (2002) 87 (8-9): 1104-1112.
... are dominantly the 1A polytype but lamellae of a 2M phase are consistently present. This is the first 2M sapphirine synthesized in the laboratory, and the first known to be devoid of Fe2+. No superstructure reflections corresponding to the doubled tetrahedral chain repeat of khmaralite were observed, probably...
FIGURES | View All (7)
Journal Article
Published: 01 October 1999
American Mineralogist (1999) 84 (10): 1650-1660.
...Jacques Barbier; Edward S. Grew; Paulus B. Moore; Shu-Chun Su Khmaralite, Ca (sub 0.04) Mg (sub 5.46) Fe (super 3+) (sub 0.12) Fe (super 2+) (sub 1.87) Al (sub 14.26) Be (sub 1.43) B (sub 0.02) Si (sub 4.80) O 40 , is a new mineral closely related to sapphirine from Khmara Bay, Enderby Land...
Journal Article
Published: 01 August 2008
Mineralogical Magazine (2008) 72 (4): 839-876.
... site with most shared edges, M7, at which the dominant cation is most often Ti (aenigmatite, rhönite, makarochkinite), Fe3+ (wilkinsonite, dorrite, høgtuvaite) or Al (sapphirine, khmaralite); much less common is Cr (krinovite) and Sb (welshite). At the fourth level, the two most polymerized T sites...
FIGURES | View All (11)
Image
Back-to-back <b>khmaralite</b> chains, with interconnecting octahedra. Beryllium c...
Published: 01 February 2009
F igure 7. Back-to-back khmaralite chains, with interconnecting octahedra. Beryllium content of tetrahedra indicated by diagonal shading, Fe 2+ content of octahedra by reverse shading, Si content of tetrahedra by background tone. ( a ) Khmaralite occupancy pattern. Note juxtaposition
Image
Crystal structure of <b>khmaralite</b>. Numbering of sites corresponds to column 1...
Published: 01 August 2008
F ig . 2. Crystal structure of khmaralite. Numbering of sites corresponds to column 1 of Table 3 (cf. column 1, Table 2 ). Oriented to facilitate comparison of site numbering with that in the makarochkinite structure shown in Fig. 3 . Green tetrahedra: Si, Si >> Be > Al or Si > Al
Image
Location of sapphirine&#x2F;<b>khmaralite</b> within the MBeAS tetrahedron, and composi...
Published: 01 August 2002
F igure 1. Location of sapphirine/khmaralite within the MBeAS tetrahedron, and compositions of starting mixtures used in this study (solid circles), 7:9:3 or Mg 3.5 Al 0 Si 1.5 O 20 and 3:5:1 or Mg 3 Al 10 SiO 20 (gray), and type khmaralite (hachured). Details of compositions A–N are provided
Image
[010] 2M  diffraction pattern from sample C, showing no <b>khmaralite</b> superstr...
Published: 01 August 2002
F igure 5. [010] 2M diffraction pattern from sample C, showing no khmaralite superstructure spots (cf., Christy 1988 ).
Image
The crystal structures of “makarochkinite” and <b>khmaralite</b>; (a) “makarochkin...
Published: 01 January 2002
Figure 10. The crystal structures of “makarochkinite” and khmaralite; (a) “makarochkinite” projected onto (001); note the chains of BeO 4 and SiO 4 tetrahedra extending parallel to the a -axis; (b) “makarochkinite” projected onto (100); circles in (b) represent interstitial Ca atoms; (c
Image
Crystal structure of <b>khmaralite</b> showing the relationship between sapphirine...
Published: 01 January 2002
Figure 2. Crystal structure of khmaralite showing the relationship between sapphirine (Spr) and khmaralite and occupancies of the tetrahedra sharing three corners with other tetrahedra (the so called Q 3 tetrahedra). Italics emphasize the alternation of ordering schemes from one sapphirine
Journal Article
Published: 01 January 2007
American Mineralogist (2007) 92 (1): 80-90.
... potentials. Welshite can accommodate up to 3.46 Be per 40 O atoms by including several T sites with 100% Be occupancies without the formation of unfavorable tetrahedral Be-O-Be linkages that would result in the related centrosymmetric structures of sapphirine, khmaralite, makarochkinite, and høgtuvaite, none...
FIGURES | View All (9)
Image
( a ) The topology of nearest-neighbor links in cyclicized versions of the ...
Published: 01 February 2009
F igure 4. ( a ) The topology of nearest-neighbor links in cyclicized versions of the sapphirine and khmaralite chains. ( b ) Topology of next-nearest neighbor links.
Image
Calculated Si contents ( a ) and Be contents ( b ) of T1-T12 as a function ...
Published: 01 February 2009
F igure 8. Calculated Si contents ( a ) and Be contents ( b ) of T1-T12 as a function of total Be, assuming interaction parameters that best fit khmaralite LRO at 1.5 Be per 12 tetrahedra.
Image
(a) A planar section of compositional space in the MgO-BeO-Al 2 O 3 -SiO 2 ...
Published: 01 January 2002
Figure 3. (a) A planar section of compositional space in the MgO-BeO-Al 2 O 3 -SiO 2 system showing the relative positions of the beryllian sapphirines synthesized by Hölscher (1987) and khmaralite with Fe 2+ combined with Mg and Fe 3+ combined with Al (modified from Christy et al. 2002 ).
Image
(b) Composition of natural and synthetic sapphirine for which ion microprob...
Published: 01 January 2002
al. 2000 , their Fig. 12). The dashed line marking a tentative boundary between khmaralite and sapphirine in natural material is based on the appearance of superstructure reflections in a natural sample containing 0.52 Be/20 O ( Grew et al. 2000 ). Type khmaralite, other “Zircon Point”, Gage Ridge
Image
( a ) Open-branched  vierer  chain of sapphirine, showing cation site label...
Published: 01 February 2009
F igure 1. ( a ) Open-branched vierer chain of sapphirine, showing cation site labels and long-range cation ordering scheme. Darker tones indicate higher Si content. ( b ) The long-range tetrahedral cation ordering pattern of khmaralite. Darker background tones indicate higher Si, whereas
Image
Diagram of the presumed crystal structure of welshite, which is taken from ...
Published: 01 October 2001
is the oxygen bridging the two most highly polymerized tetrahedra T 1 and T 4, where Be resides in khmaralite and ‘makarochkinite’.
Image
Compositional plots for Si-rich sapphirine from South Harris, which is pres...
Published: 01 October 2000
F igure 4. Compositional plots for Si-rich sapphirine from South Harris, which is presumed to be beryllian. Khmaralite composition is from Barbier et al. (1999) . Ratios refer to proportions of (Mg, Fe, Mn, Ca)O, (Al, Fe 3+ , Cr) 2 O 3 , and SiO 2 in sapphirine, e.g., 2:2:1 corresponds to 2
Image
Effect of beryllium on sapphirine unit-cell volume for synthetic sapphirine...
Published: 01 January 2002
Figure 4. Effect of beryllium on sapphirine unit-cell volume for synthetic sapphirine ( Hölscher 1987 ; Christy et al. 2002 ) and for natural sapphirine and khmaralite containing 8–10 wt % Fe ( Sahama et al. 1974 ; Barbier et al. 1999 ; Grew et al. 2000 ). The lines are least-square fits