according to this recent article entitled "Glass breakthrough," transparent aluminum (or aluminate glass) was created from aluminum oxide. it's stronger than glass and steel. however, as i looked for a photo to blog with, i found this page and another page mentioning that a ceramic research lab in Dresden, Germany created a similar material way back in 2002. perhaps the Germans discovered it first and the people at 3M figured out an easy way to reproduce it. related material: Casio's breakthrough transparent ceramic lens [via]