17Zucchelli, Christine. Stones of Adoration Sacred Stones and Mystic Megaliths of Ireland. Doughcloyne, Wilton, Cork: Collins, 2007. 16-17.
Regarding the use of quartz on the outside of the cairns, the author writes, "Spiritually, the white crystalline stone is sometimes connected with the rising sun; more commonly, however, it is linked with the moon and the female cycle."
Macalister discovered small, smooth white stone balls together with some of the internments in the cairns when he excavated them. Some, being pierced by marine mollusks, were evidently brought from the seashore. Macalister wrote: "The custom of placing white stones in interments seems to have been common in prehistoric times, and has been frequently noted. It is possible that the stones were believed to have some magical significance." (Macalister, R.A.S., E.C.R. Armstrong, and R.L.I. Praeger. "Report on the Exploration of Bronze-Age Carns on Carrowkeel Mountain, Co. Sligo." Proceedings of the Royal Irish Academy. Section C: Archaeology, Celtic Studies, History, Linguistics, Literature 29 (1911/1912): 340.)
According to archaeologist Sam Moore, "a mountain top called Croghan, which has a small passage tomb on its summit and may (incredibly tentatively as there has been no geochemistry done) be the source of the quartz for Carrowkeel, of which there is little left due to souvenir hunters." (Moore, Sam. Cairn G Roof-Box" Message to the author. 22 Oct. 2013. E-mail.)