An occurrence of native sulphur near Craignish, Argyllshire

Abstract

[Greg and Lettsom (1858, p. 19)][1] reported the occurrence of native sulphur throughout the British Isles as rare, only seven localities being detailed for England and Ireland. [Nicol (1858, p. 325)][2] and [Goodchild (1901)][3] mention sulphur as occurring in Scotland but do not specify whether this is as primary or secondary sulphur. [Heddle (1901, p. 194)][4] however, notes that sulphur resulted from spontaneous combustion of Lower Carboniferous shales containing pyrite at “several places in Scotland” and accredits it with species status. Likewise, [Shand (1910)][5] reports that sulphur resulted from combustion of pyritiferous shales in dump material from the working s at Emily coalpit, Arniston, Midlothian. In this situation sulphur appears as a powder y encrustation and additionally as minute crystals up to 0.1 mm. Indeed, two sulphur-bearing specimens from this locality are registered within the Scottish Mineral Collection. A Tertiary dyke suite, at Craignish, Argyllshire ([Allison 1936][6]) include s one dyke [NM 762 002] which approaches the “big feldspar type” of Mull in that it contains labradoritc phenocrysts up to 5 × 4 cm. A recent examination of this dyke has revealed a cavity some 10–13 cm across partially filled with a yellow-speckled ferruginous material. Marine erosion has removed the bulk of the cavity filling. Detailed examination failed to reveal other similar cavities although a pale, fawn-coloured saponite fills numerous amygdales in weathered rock. Other small amygdales (2–3 mm) are filled with thomsonite and analcime. [1]: #ref-3 [2]: #ref-6 [3]: #ref-2 [4]: #ref-4 [5]: #ref-7 [6]: #ref-1