This was found to be in error- correction is here

The artifact in question turns out to be the edge of the rover solar panel out of focus in the image.  The markings are either corrosion or frost on the edge.  The image is here at the NASA/JPL website.

Being solely responsible for the contents of this page, I have decided to keep the error clearly marked and in place so that other will not make the same mistakes.

As you can see from the inset, the upper, red outlined image is the original image that appeared to contain water.  The lower image shows the edge of the rover solar panel with the pattern of what appears to be frost on it. I have overlaid the two so you can see that the exact pattern of markings matches on both.

(previous contents, unchanged)

One of the goals of Mars research is to find water on the planet.  While checking some of the older images for geysers and water flow features, I found an image of a brine pool located in Eagle Crater early in the mission.  The reason this has not been spotted before is that the image shows just one corner of the pool, and without assembling it in relatively accurate color, the significance of the image would be easy to miss.

I will present the before and after images first, then explain how I located them.

This is the "before" image, showing a puddle of brine in the lower left corner of the image.  It was made at 12:01:24 Mars local time.  The original image is here at the NASA/JPL web site.  The image was taken with the L7 (left panoramic violet) filter.
Now we can see the "after" image which was taken at 12:02:48 Mars local time.  The original image is here at the NASA/JPL web site.  The image was taken with the R1 (right panoramic violet) filter.  Look at the lower left corner and you can see the difference- the puddle is now missing.  Spherules are in its place.

The left image shows the puddle, clearly visible to the lower left.  The right image of the exact same spot, just over a minute later, shows no puddle.  This change occurred in a space of one minute, twenty four seconds.

Note that I have kept the color saturation high in the following images to help make the features more clearly visible.  True color images would be much darker with soil about chocolate brown and the rock slabs not much lighter.  The fossil spherules in that case would be more gray than blue.

While looking at the stone slabs and the geyser vents around them, I located the pool of brine.  Here is a thumbnail of a false color image constructed from L2 and L7 data.  I used these filters because they closely correspond to the R2 and R1 respectively, and allow an excellent full color 3D image to be assembled. Click the image for a full-sized view.  The original data is here at the NASA/JPL web site.
I spotted two geysers in the above image and constructed stereo views of them.  Three features in the image stood out at once.  First, the lower center geyser itself was apparent.  Click here for a color stereo image of it.  Second, the upper right geyser was smaller but clear.  Click here for a color stereo view of it.  But finally, the undercut edge or lip showing at the lower left of the image  showed what appeared to be water erosion. I decided to try tracking the source of the water and examined all the lip features in the panoramic images for Sol 050.  This image showed the best detail.  Click it for a larger view.  It was taken at 11:56 Mars local time, just before noon.  The original image data is here at the NASA/JPL web site.

In the lower left corner, we can see an odd looking area.  Here is a closer look at it.  We see a darker outline on the rock where it is wet, and just below it, we see a brine pool.  How can we tell?  Because as the water is evaporating, the salts are concentrating and we can see the patches on the surface.  They appear bluish in this color exaggerated image. Note the soft, rounded contours to the patches and the dark level surface of the brine.  It looks completely different from the muddy soil at the lower right.