I would love to see that. Right now, you have to use a prospector on every roid to see what it contains. More often than not, 90% of them contain cheap ore that really isn't worth mining. A colour would indicate more chance of some decent ore and you'd only need to send a prospector to the one with a specific colour to see how much of the ore it contained rather than checking to see if it contained the ore you want at all. It would mean more moving around when you mine but less time and limpets spent prospecting useless roids in your search for something worth mining.