The phases are always the reverse of each other. When we see the moon as nearly full, any moon people would see a slim crescent Earth. When we see a completely full moon, the moon, Earth and sun are in a line – with Earth in the middle.
The quartz is more resistant to abrasion and chemically more resistant than the feldspar. The result is that the quartz remains in the stream but the feldspar breaks down to clay or is dissolved.
