A sample of basaltic rock from a lava flow in New Mexico serves as a calibration target carried on the front of NASA’s Mars rover Curiosity for the rover’s Canadian-made Alpha Particle X-Ray Spectrometer instrument. This image of the APXS calibration target was taken by the rover’s Mars Hand Lens Imager during the 34th Martian day, or sol, of Curiosity’s work on Mars (Sept. 9, 2012). The image has been rotated to compensate for the tilted orientation of the camera when it was taken.

The prepared slab of well-characterized dark rock collected near Socorro, N.M., is held in a nickel mounting. The circular opening revealing the rock is about 1.4 inches (3.5 centimeters) in diameter.

Probably held in place with fire-roasted cement made from Hatch chiles.