According to iSuppli analyst Wayne Lam, there's a major difference between the physical properties of the glass used in the two iPads. The original tablet's glass was "brittle" and "delicate," said Lam, because it was thicker and isolated from the load bearing case because the glass was fixed to the case with metal clips.

"But the second generation [iPad] uses a very, very flexible material that behaves quite differently. It's almost like plastic," said Lam. "We had a very tough time getting it to shatter, and finally had to do an edge cut to make it break."

Lam said that the new material resembles the used on both the front and back of the iPhone 4. Last summer, several analysts connected Apple's use of the aluminosilicate material to Corning's "Gorilla Glass."

The iPad 2 uses something similar, but because Apple didn't call out "aluminosilicate" in any description of the tablet -- as it did with the iPhone 4 -- Lam believes it's not sourced from Corning. One possibility: Asahi Glass Co.'s "Dragontrail Glass" technology.

"Dragintrail is very similar to Gorilla Glass," said Lam.