How to know if my iphone 4 back cover is glass or plastic?

How to know if my iphone 4 back cover is glass or plastic?

All iPhones are made with glass, that's why their screens are so fragile. But if you Ryan want to test it out, do the gravity test lol. Simply let your iPhone fall from maybe 5-6 ft, if it cracks, it's glass, if it doesn't, it's plastic.

All models of the iPhone after the 3GS are made of a glass front and a glass back. The iPhone 3G and 3GS are made out of plastic.