We may be looking at a sand gap

My housemate Dave and I were discussing recyclable packaging materials this evening. More specifically, we were arguing whether the new reusable-but-plastic Oystercards are better for the environment than the zillions of paper tickets they currently use on the Underground):

D: Basically, paper is the best, most environmentally friendly material because it's so recyclable.
S: Well, except glass, but it's not like you can package lots of things in glass.
D: Yeah, but glass doesn't grow.
S: But it comes from sand! There's no shortage of sand, mate*!
D: Those fucking arabs 'ave got everything.

I found this hilarious. YMMV.

* I speak Bloke when talking to my housemates.