On: Curiosity images strange metallic-looking object o...

[panacea]

Interesting theory. I had to check, and yes, Mars does have dry lightning (in dust storms).

If not that, I wonder if it's something produced volcanically like onyx.

[stock_toaster → panacea]

I was thinking an ore vein that was harder than the material around it, and said outer material had been weathered away faster to expose it.

Either that or a door handle! :P

[InclinedPlane → panacea]

Mars likely had more lightning when it was wetter, as well. Also, some Mars rocks and regolith have extremely high concentrations of Iron, so lightning induced in situ sintering of a little hunk of fulguritic Iron isn't out of the question.

The cool thing is that Curiosity is so crammed full of equipment for studying mineralogy and chemical composition that we'll likely be able to solve the riddle pretty quick.