My friend was saying that the more cargo space you have, the more chance u have getting the bigger type of minerals. Thus, increasing your income from mineral shipments

To me, I see no difference having a lot of cargo space or not

Can someone confirm this?

No it does not, your rank determines that, At rank 160 i know you start to earn Aidonuim .
Edit: But it does determine how much you can take in at one time, Say you have 1000 minerals per hour but only ave 50 cargo. You would get half the shipment one click then get half the next click, more cargo just makes it loook like you get more but really you get the same amount as you would just more clicks.

I believe there is some truth to it, because you can take in more minerals and more of a % can be proportioned to the higher end minerals.

Let's say, from an abstract point of view, that if you could ONLY get Dynite, Chrisium and Darrinyte, and the haul ratios are set like this:
Dynite = 50%
Chrisium = 35%
Darrinyte = 15%

If your haul was of 20 minerals you would get
Dynite = 10
Chrisium = 7
Darrinyte = 3

However, if you only had 1 cargo space left (i.e. only take in 10 minerals), your haul could look like this:
Dynite = 5
Chrisium = 4
Darrinyte = 1

This is because the game would round the lower value minerals up first - so you should get 3.5 Chrisium, which can't happen, so it's rounded up to 4. 10-5-4 only leaves 1 left, not 1.5, so you'd be missing out on 1/2 a Darrinyte. I know this isn't a lot, but what if it was a shipment of 2000 minerals? and you got an extra 100 Kurenite instead of 100 Aidonium. THEN you would start see a difference.

What I'm trying to say is that if you can't take the whole shipment, the game will most likely round DOWN instead of up, and you may lose out on a lot of money.

Dan has said somewhere (its buried in the archives here) that free cargo space does not effect the chances of getting any type of minerals. This however, was before the introduction of Aidonium, which for those who dont know, takes up 5 cargo space instead of 1. IDK for sure but there is a possibility that in the event of someone having an open amount of cargo space that is not divisible by 5, the remainder could no longer have a chance of being Aidonium thus reducing your chances of getting it. Or by having open cargo that is divisible by 5 when the mineral point that is calculated to be something other then Aidonium when there is 5 space left could cause you to loose out as well. I havnt tested any of this, but I belive there may be a chance that due to a person having more mineral points then they have cargo space they could loose out on a single Aidonium each time they have to receive minerals.

As for the other minerals, no having more cargo space will not effect how much of each mineral you get per shipment.

All minerals except Aidonium are 0.1 in size.

Dude, Coth knows what he's talking about, its just a typo.

The only time when Coth knows what he's talking about it's when the topic is ponies. Fact.