What is the back of the iphone 5 made out of?

I'm deciding whether to get the iphone 5 in black or white and i can't find it anywhere but what are both of the iphone's backs made out of? I'm leaning towards white right now because it had the aluminium side like the 4s does but could anyone offer a insight to why apple decided to do this?

What do you have to do with the back? Just see the features and BUY it!

It's aluminum

Okay If you don't know what to choose between the black and white I'd say see more picture of it and decide but i personally always loved the white iPhone over the black one but now with the iPhone 5 I like the black one much more because on the back it looks sexier:-p just my opinion.
from what is the back made well you almost said the whole thing, aluminum as a unibody with two glass pieces on the top and the bottom.
as for your wonder why Apple did this, well from my opinion i think that is a genius engineering, basically the reason why they have aluminum is to make the phone stronger and thinner because with glass they need to make it thick enough to sustain everyday activities but the aluminum now they can make it thinner and still be strong enough, also if you are wondering why they still have two glass piece at the top and bottom of the back well, it is because now it has LTE so they need more and bigger space for antennas because now they should include bluetooth, GPS, EDGE, CDMA, 3G, LTE, Wi-Fi etc.antennas and that is hard to be all just on the edges of the phone like the iPhone 4 therefore, they decided to move some of those network's antennas to the glass pieces on the back because aluminum can't be used as antenna but glass can.
and also one more genius engineering is that they made the phone taller only rather than taller and wider like many other phones. That by it self will solve a lot of problems.
see those black gaps you find on the top and bottom of the video that you are watching on your iPhone?
those are going to be going or at least there will be only very tiny ones that you barely can see because the ratio changed therefore you can watch videos fully without having to lose a part of the video, also not making it wider allows you to still be able to use your phone with one which yes isn't as good as with two but at least you still can rather than you can't at all.
I highly recommend the phone, it is an excellent device, from all perspectives I think.
i really hope that helped you, and oh you should watch this to know more

http://www.apple.com/...one/#video
you probably have seen it already, hehehe