Alrakis

Alrakis was the home planet of the Tonska until they were destroyed by a mobile temporal rift

Alrakis orbited the star Iota Ophiuchi and was a violet colour from space due to its violet atmosphere. It had single large moon, which was mined extensively by the native Tonska and which had a decaying orbit, causing it to crash into Alrakis thousands of years after the Tonska had vanished. (VD: ...And Eternity in an Hour)