cryptic

A secondary electron image of an etched cleavage surface of a K-feldspar. The near vertical lines are cleavage edges and the diagonal streaks are perthite exsollution lamellae. The bigger ones at the top and bottom are microperthite and can be seen (just) with backscatter. The very very fine streaks in the centre band (they are there... look closely) are cryptoperthite - they are so small and fine that you can only see them by etching.

Done