by rstevenson » Tue Jul 13, 2010 10:06 am
Ann wrote:Is it really true, though, that the Earth is mostly made of rock? I thought it was mostly made of iron and nickel. Perhaps iron and nickel make up most of the Earth's mass, but rock makes up most of the Earth's volume?
By coincidence, I was paying attention in class last week.
Counting the atmosphere, the earth is about 50% oxygen with half the remainder being silicon. Then there's a bunch including (in descending order) aluminum, iron, calcium, sodium, potassium and magnesium. At that point we're below 1% for each of the rest of the elements.
I find it interesting that we think of the earth as having lots of nickel in its core, and there certainly seems to be plenty in the upper crust for mining, but it doesn't even make the list in my textbook. An on-line reference tells me it makes up only 0.018% of the total. Iron, by the way, is number four in the list with less than 5%.
Of course "rock" is made up of lots of things including silicon and oxygen and carbon and ... . And since a whole lot of rock contains those top two elements and many others near the top of the list, I suspect that yes, the earth can be said to be mostly rock, though a good deal of it would be molten.
Is there a geologist in the house?
Rob
[quote="Ann"]Is it really true, though, that the Earth is mostly made of rock? I thought it was mostly made of iron and nickel. Perhaps iron and nickel make up most of the Earth's mass, but rock makes up most of the Earth's volume?[/quote]
By coincidence, I was paying attention in class last week. :shock:
Counting the atmosphere, the earth is about 50% oxygen with half the remainder being silicon. Then there's a bunch including (in descending order) aluminum, iron, calcium, sodium, potassium and magnesium. At that point we're below 1% for each of the rest of the elements.
I find it interesting that we think of the earth as having lots of nickel in its core, and there certainly seems to be plenty in the upper crust for mining, but it doesn't even make the list in my textbook. An on-line reference tells me it makes up only 0.018% of the total. Iron, by the way, is number four in the list with less than 5%.
Of course "rock" is made up of lots of things including silicon and oxygen and carbon and ... . And since a whole lot of rock contains those top two elements and many others near the top of the list, I suspect that yes, the earth can be said to be mostly rock, though a good deal of it would be molten.
Is there a geologist in the house?
Rob