What is the Iron Mass in the Main Asteroid Belt?

[dBrandon/dC]

I'm trying to find how much iron (by mass) is in the main asteroid belt. I'm finding a lot of sites that say 10% of the asteroids are M class, but is that by number or by mass? Does anyone know, and can you provide a reference?

 

[chasrob]

Wikipedia says the total mass in the belt is 3.0 to 3.6E21 kilograms-
http://en.wikipedia.org/wiki/Asteroid_belt#Characteristics
So 10%--3.0 to 3.6E17 tonnes.

That's figuring M-type are all nickel-iron, which is unknown. Many other types have iron--Vesta is believed to have a nickel-iron core, eg.http://en.wikipedia.org/wiki/4_Vesta#Geology

 

[Chronos]

Population demographics of the asteroid belt
1] class M [metallic] 10%
2] class S [stony] 15%
3] class C [carbonaceous] 75%
These are by count and predominant spectral characteristics. The relative mass composition is not well known for obvious reasons. The aggregate iron content is probably about the same as that of Mars crust [estimated around 5%].