Heliodor with a Large Schorl Inclusion
An 8.33 ct long rectangular heliodor, the yellow variety of beryl (ideally Be3Al2Si6O18), was examined by the author. It was reportedly from the Zelatoya Vada mine in Murgab, Tajikistan; however, it was likely from Pakistan (J.S. White, “Let’s get it right: Tajikistan heliodor,” Rocks and Minerals, Vol. 80, No. 4, 2005, pp. 285–286). The heliodor had a large schorl tourmaline inclusion prominently under the table facet (see above) and a small schorl tourmaline near one corner. A thin band of fine fluid inclusions ran parallel to the length of the stone adjacent to the tourmaline. The stone was clearly cut to highlight the interesting inclusion rather than hide or remove it; aside from the two tourmaline inclusions and the thin band of fluids, the beryl had high clarity.
Both the heliodor and the tourmaline were analyzed by Raman spectroscopy and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) to better understand the structure and chemistry of the minerals. Analyses were conducted on the girdle of the heliodor and on the back end of the tourmaline inclusion where it intersected a pavilion facet. The heliodor had low-moderate water bound in its structural channels, as determined qualitatively by Raman spectroscopy, which is expected for heliodor with low sodium content (R.E. Henry et al., “Crystal-chemical observations and the relation between sodium and H2O in different beryl varieties,” Canadian Mineralogist, Vol. 60, No. 4, 2022, pp. 625–675). The heliodor fit well within the expected chemistry; it had low overall cation substitutions, with minor or trace iron, magnesium, lithium, sodium, and cesium content. The tourmaline was confirmed to be schorl dominant due to its predominant sodium and iron content; however, due to high vacancy at the X structural site, the tourmaline had a high foitite component (D.J. Henry et al., “Nomenclature of the tourmaline-supergroup minerals,” American Mineralogist, Vol. 96, 2011, pp. 895–913).
After data collection for research, this stone will be used in the GIA GemKids program as an educational piece for young students at the Carlsbad campus. It will represent the heliodor variety of beryl, showing fascinating inclusions as well as evidence of LA-ICP-MS laser pits on the girdle of the stone (not shown in the photomicrograph).
