They found 'hydrated sillica' on Mars. That's opals, baby.
This is exciting for several Sci-Fi worthy reasons:
1. It means water was free-flowing on the surface for long enough to change the chemical composition of the surrounding bedrock in very specific ways that mean it lasted longer then previously thought-- bringing a watery Mars into the timeframe of life development here on Earth (though it was still gone long before modern humans; not before archaic humans, though, and it just sparks the imagination all over the place to think that proto and early humans might have looked up and seen a blue dot where we see a red one...).
1a. This means there might have been life on Mars and it might have lasted long enough to grow big enough that we could find fossils with the naked eye, if we can find the sorts of terrain that would expose fossils in a weather-system entirely unlike ours.
2. It gives a reason to go to Mars and an industry to pay for it. Opals are expensive and still moderately rare here; Mars opals would be so much more exotic, rare and astronomically expensive, but if they're gem-quality in sufficient quantities, they'll pay back the cost of getting there to bring them back almost immediately. Seriously, who wouldn't want a Mars opal? And we know from experience that greed is a faster motivator for expansion and colonization for people then humanitarianism ever was, so why not prey on rich people's need to get more rich as a way to get the scientists and colonists over there? C'mon! It's brilliant! It'll be stupid-expensive, but it can be done in my lifetime!