Cassiterite, wolframite, coltan: they might be the spoiled offspring of celebrity parents, or characters from an unfamiliar fairytale. The truth is much more prosaic. They are the minerals on which laptops and mobiles and even the tin of tomatoes in the cupboard depend. Cassiterite is the main component of tin oxide. Wolframite is a source of tungsten, used in many electrical applications. Coltan makes mobile phones work.