In various ancient authors (e.g. the ‘Argonautika’ of Apollonios Rhodios) curious news about the Island Elba can be found, concerning the existence, somewhere on the shore near Portoferraio, of pebbles that are ‘dirty’ from the Argonauts’ sweat. The Argonauts are said to have stopped on the island during their journey back from the looting of the ‘Golden Fleece’. These pebbles are found to be typical of the gravelly beaches below the Capo Bianco cliffs. Such walls are made up of a bony-white aplitic rock dotted with blue-black tourmaline spots. Capo Bianco aplite is the uncommon result of the solidification of a boron-rich magma in a subvolcanic setting. Here, the separation of a boron-rich fluid phase gave way to the crystallization of peculiar spherical dark tourmaline spots in a very fine-grained white groundmass. This rock was noted by Argonauts (i.e. the ancient travellers they represent) and used as a lighthouse to the harbour of Argoos limen (now Portoferraio). Also in the myth, the unique mottled pebbles were recorded as stained by the Argonauts’ sweat. The occurrence, within the same, complex myth, of ‘data’ concerning navigation (the white cliffs) and geology (description of the spotted aplite) identify the Argonauts as a blending of mineral prospectors, explorers and early eighteenth century-like naturalists, legitimatizing the commercial/political presence of Greeks in the region. Fanciful tales or myths have arisen during the course of each culture’s history, most often from either religious or social motivations. In some cases, a pre-scientific view of the natural world generated observations that became a relevant element of the structure of the myth. Only with progress in the scientific analysis of nature, perhaps first truly introduced by Herodotus, have we gradually developed a distinction between natural and mythical explanations. One aspect of myths is that they often recall specific places in which special or peculiar natural features are present, and for this reason, the Island of Elba could not be absent in the ancient mythology. In fact, this island has a privileged position for navigation in the central Mediterranean Sea, being located between Corsica and the Tuscan shoreline, and it was also famous in the classical world for its iron deposits, noted by Ps. Aristoteles (De Mirabilibus Auscultationibus, 93), Vergilius (Aeneis, X, 143–144) and Strabo (Geography, V); see also Corretti (2004a) and references therein. In particular, Elba occurs in the myth of Jason and the Argonauts that was codified by Apollonios Rhodios who describes the exceptional character of some unique rocks (perhaps the Capo Bianco aplite) as having both a special petrographical and mineralogical nature, as well as an extraordinarily bright, white colour of outcrop. In this paper we describe the geology and petrology of the tourmaline-rich Capo Bianco Aplite cropping out as a dismembered laccolith along the northern coast of central Elba, and we highlight the strict similarity between the petrographic features of the Capo Bianco rocks and the descriptions contained in the Argonauts’ myth reported by Apollonios Rhodios. Finally, we discuss how accurate observations on this oddity of nature were ‘metamorphosed’ in the structure of a mythic narration. The Tuscan Magmatic Province and the Island of Elba granitic rocks