Sol 4253: Mars Hand Lens Imager (MAHLI)

looks similar to desert varnish

https://en.wikipedia.org/wiki/Desert_varnish

https://www.nps.gov/articles/desertvarnish.htm

"The varnish is primarily composed of particles of clay along with oxides of iron and manganese. There is also a host of trace elements and almost always some organic matter."

Sol 4253: Mars Hand Lens Imager (MAHLI)

This image was taken by MAHLI onboard NASA's Mars rover Curiosity on Sol 4253 (2024-07-24T03:10:00.000Z)

Credits: NASA/JPL-Caltech/MSSS

 Sol 4253: Mars Hand Lens Imager (MAHLI)

This image was taken by MAHLI onboard NASA's Mars rover Curiosity on Sol 4253 (2024-07-24T03:15:31.000Z)

Credits: NASA/JPL-Caltech/MSSS