This photo was selected by public vote and featured as "Image of the Week" for Week 152 (January 7 - 13, 2024) of the Perseverance rover mission on Mars. Perseverance rover acquired this image using its Right Mastcam-Z camera at full zoom. Mastcam-Z is a pair of cameras located high on the rover's mast. This image was acquired on January 9, 2024 (Sol 1027) at the local mean solar time of 12:23:19. Image Credit: NASA/JPL-Caltech/ASU/MSSS
From what I have read: A combination of metallic salts, iron, sulphur, clay and chalk... BTW the salts (perchlorates) in the dust would probably kill you.