Pinky stone

If you visit Rosemarkie beach on the north eastern coast of Scotland, it is not difficult to find pinkish coloured stones and rocky outcrops. (See also extra picture.) I assume this stone is quartz, but where does the colouring come from? My first thought was jasper, although I’ve had folk say it’s sandstone. Excuse me, but sandstone buildings are not pink. Are there any geologists out there?
    I was editing and spellchecking this morning until I felt a headache coming  on. So I stopped.