What is "schiller" ?
- a blue-white sheen seen as light passes over the surface
(it's caused by a mineral unmixing phenomenon that forms two
feldspars with different compositions!!)
- at high temperatures, the Na and K fit easily into 'holes' in the
- when the crystal is cooled in a rock, the Na and K are no longer so
- thus, the mineral separates out into
- light is scattered by the intergrowth