Corning experimented with chemically strengthened glass in 1960, as part of an initiative called "Project Muscle". Within a few years they had developed what they named "gorilla glass". However, Corning could find no practical use for the glass at the time and "gorilla glass" was never put into production. In 2006, Apple Inc. was developing what was to be the first model of the iPhone. Though initially it was to have a hard plastic screen, Steve Jobs found that when placed in his pocket his keys scratched the prototype's surface. Jobs was outraged and resolved to find a glass that was scratch-resistant enough that iPhone buyers wouldn't have the same problem. Jobs ended up contacting the CEO of Corning, Wendell Weeks and told him that Apple needed a light yet strong enough glass screen for use in their consumer devices. Weeks told him of the "gorilla glass" that the company had developed in the 1960s but had since been mothballed. Jobs convinced Weeks to immediately put the glass into production for use in the upcoming iPhone. Despite initial skepticism on Weeks' part that Corning could do so and also be able to manufacture enough screens in time for the iPhone's pending release, they did in fact achieve these aims within six months. Corning's Harrodsburg, Kentucky factory was able to supply enough "gorilla glass" screens for Apple's iPhone release in June 2007. Thereafter, Corning's revived Gorilla Glass project started to develop this tough cover glass for a range of smartphones and other consumer electronics devices for multiple companies. Alongside smartphones, Gorilla Glass is also used in tablets, notebooks and TVs.
Gorilla Glass' most useful qualities are its strength, scratch resistance and thinness.
Because of corundum's hardness (pure corundum is defined to have 9.0 Mohs), it can scratch almost every other mineral.
It commonly occurs as a detrital mineral in stream and beach sands because of its hardness and resistance to weathering.