I can give you an average number for the Earth's crust: 46.6% oxygen The Earth's crust is made up of many different types of minerals ( >4,000). As you probably guessed, the percent of oxygen in minerals is different for different types of minerals.

This is an interesting fact: researchers at NASA are looking into oxygen-containing minerals on the moon's surface as a potential source of oxygen. One mineral in particular, ilmenite, contains about 10% oxygen by weight and when heated gives off that oxygen, so could be used o create oxygen for astronauts living in a colony on the moon, something President Bush has included in his space exploration plan. NASA has hopes to send astronauts to the moon by 2018. You could be one of them!

Quartz has two atoms of oxygen and one atom of silicon. Olivine has four atoms of oxygen, one of silicon, and two of either iron or magnesium. Ice has one atom of oxygen and two of hydrogen.

So, by number of atoms, quartz, olivine, and ice, have 2/3 (67%),4/7 (57%), and 1/3 (33%) oxygen, respectively. I would need to calculate how much that is by weight, but suffice it to say that much of the mass of the Earth's minerals is oxygen, somewhere around 50%. Of course, the Earth's core is made out of iron.