Normal window glass is Mohs hardness 5.5 or so, as is unhardened steel (your fork and pocketknife); hardened steel (e.g. a metal file) is more like 6.5. That means you can scratch regular steel with glass and vice versa, with some difficulty. (Try it. I just did.) Brass (your key) is around 3 or 4, so it won't scratch glass.
There are lots of things with Mohs hardness above 5.5, including most common metals (except brass, aluminum, copper) and most rocks.
Sand is almost never made up of glass particles. It's often made up of crystalline quartz (Mohs hardness 7) which can scratch regular glass easily. Gorilla Glass has Mohs hardness of about 9, so quartz won't scratch it.
http://www.corning.com/docs/specialtymaterials/pisheets/PI23... gives its Vickers hardness as 701 kgf/mm^2, which http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness#... would seem to place in the 5-6.5 range of the Mohs scale, nowhere close to 9. However, Vickers is a scale of resistance to plastic deformation, while Mohs is a (highly nonlinear!) scale of resistance to abrasion, so perhaps take that with a gram of potassium chloride.
Other random places suggest sapphire's Vickers hardness is around 1800-2200 kgf/mm^2, which is substantially harder than the number Corning's brochure gives for Gorilla Glass.