This image shows different classes of rocks explored by the Rover.
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Image from: JPL/NASA

Classes of Martian Rock

The rocks explored by the Mars Pathfinder's Rover have been classified into three kinds by scientists analysing the Rovers' findings. Potentially the rocks may all be the same kind of rock, all having an origin at a rocky outcropping 30 kilometers away. Chemical analysis of the exterior crust of the rocks suggests that they may all be nearly identical. On the other hand, the rocky exteriors may all be covered with what scientists call a "weathering rind", so the true nature of the rocks may be hidden from the Rover's instruments.

Nevertheless, scientists can see three basic differences in these rocks. These differences help them figure out more about weathering processes on Mars and where the soils surrounding the rocks may come from. The three classes are:

  • dark,
  • bright, redder than the dark rock, but not at red as pink
  • pink, perhaps covered with a red substance which has an iron oxide (rust) component

Different classes are pointed out in the image to the left. Green arrows show dark rocks, the white arrow shows pink rock. Barnacle Bill was a dark rock, suggesting that it may be a basalt. Scooby Doo was a pink rock suggesting that it may be composed of drift material which became cemented together.

The rocks were also classified into two groups according to how they weathered. Differing weathering properties may indicate differing conditions of deposition; impact i.e. coming from a crater impact, or fluvial i.e. coming from flowing water.

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