I must have misread that bit.
Now take it a step further... what is the average mineral amount on an asteroid? And how long would it take to be mined out?
It varies way too much to categorize. Most Asteroids aren't even worth mining. But some are exceptionally rich.
In my current Conventional-start game, I have an asteroid with 215,000 Uridium (1), 129,000 Gallicite (1), 52,000 Vendarite (0.9) and 21,000 Duranium (0.9). Another with 83,000 Duranium, 85,000 Vendarite, 43,000 Neutronuim, 29,000 Boronide and 18,000 Uridium (all 0.9).
These deposits would be pretty decent
for a Home World.
These are of course very rich Asteroids... but it only takes ONE of them to pay for your entire ship-building program.
Comets are more dependable, almost always having several deposits of tens-to-hundreds of thousands of minerals in the 0.8+ range.
![](http://i11.photobucket.com/albums/a155/blueemu/CometMines.jpg)