English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Four colorless tourmalines of the liddicoatite-elbaite series from pegmatites from Anjanabonoina, Madagascar, have been characterized by crystal-structure determination and by chemical analyses. Optimized formulae range from  X (Ca 0.57 Na 0.29 □ 0.14 )  Y (Al 1.41 Li 1.33 Mn 2+  0.07 □ 0.19 )  Z Al 6  T (Si 5.86 B 0.14 )O 18  (BO 3 ) 3  V (OH) 3.00  W [F 0.76 (OH) 0.24 ] [a = 15.8322(3), c = 7.1034(3) Å] to  X (Na 0.46 Ca 0.30 □ 0.24 )  Y (Al 1.82 Li 0.89 Fe 2+  0.01  Mn 2+  0.01 □ 0.27 )  Z Al 6  T (Si 5.56 B 0.44 )O 18  (BO 3 ) 3  V (OH) 3.00  W [(OH) 0.50 F 0.50 ] [a = 15.8095(9), c = 7.0941(8) Å] (R = 1.3.1.7%). There is a high negative correlation (r 2  = 0.984) between the &lt;T-O&gt; bond-lengths (~1.618.1.614 Å) and the amount of  IV B (from the optimized formulae). Similar to the olenites (from Koralpe, Austria) the liddicoatite-elbaite samples show a positive correlation between the Al occupancy at the Y site and  IV B (r 2  = 0.988). Short-range order configurations show that the presence of  IV B is coupled with the occupancy of (Al 2 Li) and (Al 2 □) at the Y site. The structural formulae of the Al-rich tourmalines from Anjanabonoina, Madagascar, show ~ ⃞ 0.2  (vacancies) on the Y site. We believe that short-range order configurations with Y(Al 2 □) are responsible for these vacancies. Hence, an oft-used calculation of the Li content by difference on the Y site may be problematic for Al-rich tourmalines (olenite, elbaite, rossmanite). Fourier transform infrared (FTIR) spectra were recorded from the most  IV B-rich tourmaline sample. The bands around 5195 and 5380 cm -1  can be assigned to H 2 O. Because these bands still could be observed in FTIR spectra at temperatures from -150 to +600 °C, it seems unlikely that they result from H 2 O in fluid inclusions. Interestingly, another FTIR spectrum from a dravite in which the X site is filled completely with Na, does not show bands at ~5200 and ~5400 cm -1 . Although not definitive, the resulting spectra are consistent with small amounts of H2O at the X site of the elbaite. The rare-earth element (REE) pattern of the B-rich elbaite (ΣREE: ~150 ppm) demonstrates that this sample is strongly enriched in LREEs compared to HREEs and exhibits a negative Eu anomaly. This sample shows the strongest enrichment of LREEs and a high La N /Yb N  ratio of ~351, which seems to confirm an important role of the fractional crystallization process.

american mineralogist

Tetrahedrally coordinated boron in tourmalines from the liddicoatite-elbaite series from Madagascar: Structure, chemistry, and infrared spectroscopic studies