Probably the most obvious property of a mineral is its colour. 'White' light contains a range of visible wavelengths from red to violet, but the mixture of colours is perceived to be white. When white light falls on an object some wavelengths are reflected, some are absorbed. The object then appears to be a particular colour because those absorbed wavelengths are missing from the reflected spectrum. The same happens when light passes through an object, which is the case with transparent and translucent minerals. A given crystal absorbs a particular range of wavelengths so that the colour of the light emerging from it depends on the type of mineral it is.