It's difficult to loft sand on Mars. Dust is another matter. Can you clarify conditions necessary to produce a full on sandstorm on Mars and whether those conditions have ever been observed?

The "rotten" appearance of the light colored rock may argue against a sand-worn explanation. Nevertheless, remnant sand or grit is observed on the surface of these outcrops, and it must have got there somehow!

Some of the spheres are neatly sliced in half. Does this propensity to cleave so neatly have something to do with their production? Do precipitated spheres have this ability to come apart in halves? Would erupted spheres do this?

Is the "soil" (which appears to be a crystalline grit or sand) the result of erosion of both the softer light colored rock and the darker, harder spheres?

Aren't there spheres at the Spirit site as well?

(BTW, thanks for sharing your thought processes, image processing and your insights! This is all really exciting. Cheers, BRF)