From Exsolution to 'Gold Sheen': A New Variety of Corundum

Synthetic Emeralds Grown by W. Zerfass: Historical Account, Growth Technology and Properties

“…In agreement with previous studies (e.g. Palanza et al, 2008;Bui et al, 2015), Raman spectra of the inclusions consisted of superimposed signals from both the host sapphire and the tiny inclusions. Figure 5a illustrates the spectrum of sapphire (α-Al 2 O 3 corundum), including peaks at 379, 418, 430, 449, 576 and 750 cm −1 .…”

“…High magnification revealed their plate-like shape (Figure 4b), with edges parallel or perpendicular to the acicular inclusions. Their appearance was similar to the magnetite inclusions found in 'Gold Sheen' sapphires (see Figure 13 in Bui et al, 2015). In the present case, however, these black inclusions were isolated from the networks of acicular inclusions.…”

“…The obtained spectra are in good agreement with natural ilmenite (e.g. Rull et al, 2004Rull et al, , 2007Bui et al, 2015) and pure synthesized ilmenite (e.g. Sharma et al, 2009;Guan et al, 2013).…”

Hematite Exsolutions in Corundum from Cenozoic Basalts in Changle, Shandong Province, China: Crystallographic Orientation Relationships and Interface Characters

“…(2) open system replacement reactions along the cleavages and other defects [20]. (3) closed system exsolution [9,10,12].…”

“…He et al (2011) studied TiO2 in corundum and found that twinned α-TiO2 transformed to rutile structure at specific temperature [11]. Bui et al (2015) studied ilmenite exsolutions in asterism corundum by Raman spectroscopy and found that ilmenite exsolutions occurred in four arrays elongated parallel to the cleavage cracks [12]. Furthermore, interface structures between hematite-corundum phases have been researched.…”