Spodion est res cuius origo nos latet: res tamen adusta videtur Avi. dicit radices canarum adustarum.
Spodion is a substance whose origin lies concealed from us, but it appears to be a burnt substance. Avicenna says it is the roots of singed canes.
Simon is referring to the Canon Avicennae, Capitulum 617. De spodio (annotation: thabasir): Spodium quid est? Radices cannarum ... adustae. Dicitur enim, quod ipsae aduruntur propter fricationem suarum extremitatum, cum ventus eas perflat. "What is spodium? The singed roots of canes. It is said that these are singed because of the friction caused when the wind blows over their outer layers".
For more on spodion meaning "Tabasheer, bamboo manna" see Tabaisir.