One of the most interesting discoveries made by Mars Rover Opportunity, was the discovery of small spheres ("blueberries") that covered the rover's landing site.
They have a few millimeters in diameter and freely on the surface of the Red Planet, and sometimes are found in outcrops of rocks.
Balls outcrop of Cape York (here and below the image NASA / JPL-Caltech / Stuart Atkinson).
An analysis conducted Opportunity, has shown that it is most likely, a certain type of nodules, which can be found on Earth — in the outcrops of the geological formations, the Navajo Sandstone in the U.S. state of Utah (the so-called marble mokvay formed by groundwater). It turned out that the beads contain hematite. This material has been found to orbit in the region and that is why the rover sent to Meridiani plateau.
Now, eight years later, the rover found another type of balls. They are generally similar to the previous ones, but rather densely packed in an unusual outcrop, located on the east side of Cape York Peninsula, a small ledge, and indeed reminiscent of the Cape (cape), on the edge of a huge crater Endeavour. Outcrop is located in an area with which the orbit was defined as having a small deposit of clay. Further south along the rim of the crater is, apparently, a significant deposits of clay — to "Cape Tribulation» (Cape Tribulation), where Opportunity has not yet reached.
These beads are interesting primarily because they can be associated with clay deposits (is there actually clay or not, is still unknown.) Their dense concentration and the physical nature of the exposures themselves point to a different origin than previous spheres, especially since the hematite from orbit is not considered (maybe it here just a little).
Opportunity is interested in clay deposits in this area, primarily because they could be formed in the non-acidic (pH-neutral) water, as often happens in the world. However, as we recently learned, the origin of the Martian clay remains a subject of debate.
One way or another, but the whitish gypsum veins are found in Cape York, seen by some as an indication of the presence of water in the distant past. Nearby there are other deposits of bright colors, but their composition, nothing is known.
Part of the outcrop of Cape York.
Prepared according to Universe Today.