According to Appleosophy, these are going to be some of the newest wallpapers for macOS Mojave, which is set to be released sometime this fall. 

These wallpapers come from the newest version of the macOS Mojave beta that was released to the developers yesterday.

All of the following wallpapers will work with the 12-inch MacBook, MacBook Air, MacBook Pro, iMac, Mac Pro and Mac Mini. Simply click and drag the wallpaper(s) you want to your desktop and then make it your background in settings. Enjoy!

Desert-1Chroma-2Chroma-1Abstract-Shapes-2Abstract-4Abstract-3Abstract-2Abstract-1Reflection-4Reflection-3Reflection-1Flower-6Flower-5Flower-4Flower-3Flower-2Flower-1Desert-7Desert-6Desert-5Desert-4Desert-3Desert-2