I have never been able to understand why some beaches, as at Sanna, are almost exclusively sand, while others, such as this one to the east of Coiremhuilinn, is shingle, cobbles and rocks. Somehow, a sand beach is more appealing, but one of the pleasures of walking the rocky beaches along the south shore of Ardnamurchan is the variety of rocks which have accumulated there. Each rock tells a story, some of which are as much as a billion years old.
This is a relatively much younger igneous rock, something like a granite, which was intruded into the pre-existing rocks as a molten liquid and then cooled slowly underground - hence the large crystals of lighter-coloured minerals such a quartz and felspar, with some darker minerals which may be a mica such as biotite. The nearest granite to here is at Strontian.