Jewel in your hand(set)
Since the introduction of the iPhone, Corning has made a number of improvements to Gorilla glass, which Apple reportedly still uses in today's devices. The third version of the material, for example, was designed with a process that models its composition down to the atomic level, and results, according to Corning, in more than three times more resistance to damage than the original.
Still, if you own an iPhone, iPod touch, or iPad, chances are that cracks and scratches are still very much on your mind--which, perhaps, explains the healthy number of cases and screen protectors that are widely available from third-party manufacturers. If you're like me, you may have even taken to carrying your phone in a dedicated pocket, cramming your change and house keys in the other just so that the two don't accidentally come into contact.
It's likely that this fact hasn't escaped Apple's design team, either, which may have led the company to look beyond glass and into the manufacture of a different medium for its screens: sapphire.
Although its name may evoke the image of beautiful blue gemstones--the color is the result of iron and titanium impurities--pure sapphire is actually transparent, and an excellent conductor of all the wavelengths that make up visible light. Made primarily of aluminium and oxygen molecules arranged in a crystalline structure called corundum, it sports a Mohs value of nine, making it the third-hardest known material after diamonds and an exotic mineral called moissanite--both of which are far too expensive for use in a mass-market product.
Time and pressure
Alas, Apple can't go mining "natural" sapphires big enough to cover an entire iPhone screen--even if they did exist, they would likely present any number of defects and impurities that would make them completely unsuitable for mass production.
Instead, Apple has built a facility in Arizona that will allow the company to manufacture synthetic sapphires; although the exact process used by Apple isn't known, sapphire production usually involves either "growing" it from a seed crystal (a technique for which the company already owns a patent), or forming it by subjecting its base components--aluminium and oxygen--to extremely high pressure from all sides until they coalesce into the finished material.
Interestingly, sapphire is actually heavier than Gorilla glass--given two panes of the same thickness and size, the former will weigh roughly sixty percent more than the latter. However, because of its higher strength, one needs far less sapphire, which could make devices that use it both lighter and thinner.
Sapphire is already widely used in a number of common applications; for example, the front plates of many high-end watches are made with it, and even Apple has been employing it to cover the camera lens of recent iPhone and iPad models, as well as the Touch ID sensor on the iPhone 5s. As a material, it adapts without problems to industrial automation and its characteristics have been widely researched.
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