Number and Amount

[ngoc_lan]

Can you tell me how to use "Number" and "Amount" correctly? Please give me some examples if you don't mind.

Which is the most suitable for this sentence?
Many of the minerals near the Earth's surface exist(s) in small ____________.
(I'm not sure if either exist or exists is correct. Help me with this, too!)

One more thing, please! Are there any difference between "a number of" and "the number of"?
Thanks for all your help.
ngoc_lan

[Tdol]

What do you think? Give us your idea first.

[BobSmith]

Many of the minerals near the Earth's surface exist(s) in small . quantities .

.

[ngoc_lan]

What do you think? Give us your idea first.

I think "minerals" is a plural noun, so I'll complete that sentence like this:
Many of the minerals near the Earth's surface exist in small number.
I'm not sure if it's correct. Please correct it!
Thanks.

[Raymott]

I think "minerals" is a plural noun, so I'll complete that sentence like this:
Many of the minerals near the Earth's surface exist in small number.
I'm not sure if it's correct. Please correct it!
Thanks.

No, that's wrong, so is 'amount'. You need to write 'amounts'.
Gold exists in a small amount. Silver exists in a small amount. These minerals exist in small amounts.