One of the ways scientists collect mineralogical data about rocks on Mars is to view them through filters that allow only specific wavelengths of light to pass through the lens of the panoramic camera. NASA's Mars Exploration Rover Spirit took this false-color image of the rock nicknamed "Tetl" at 1:05 p.m. martian time on its 270th martian day, or sol (Oct. 5, 2004) using the panoramic camera's 750-, 530-, and 430-nanometer filters. Darker red hues in the image correspond to greater concentrations of oxidized soil and dust. Bluer hues correspond to portions of rock that are not as heavily coated with soils or are not as highly oxidized.