Not the worst, but there's room for improvement
Let's start off with the good. Music? Fantastic. It had me in all the time, and you picked some really decent tracks. And you really can't go wrong with this gameplay. Sure, the armor didn't add anything, but i do appreciate the look, no doubt. It looks graphically appeasing, that's for sure. Sound flowed well, and framerate was decent. Overall, as a shooter, it would be a good thing
So why a 7?
Why don't you just call the mineral "Unobtainium" and go from there. I wouldn't call this a "halo ripoff" because, honestly, it's not hard. If i didn't want a story to go along with it, there's a handful of games like yours out there. It was decent enough and looked good, sure, but a game without a decent story isn't worth it in this day and age. It's like making a cake: after you've made a good center, are you going to frost it with a good, plot driven, icing, or dull, overdone mercury. The taste WILL change, i assure you.
So, this is a good start. Hell, it's a FANTASTIC start, but please, give us something more!