The Complete Miner's Guide by Halada42
10.1 Is Mercoxit mining still hot?Yes it is, but it only becomes lucrative at Exhumer 5. Many pilots stop at Exhumer 4 since for Hulk pilots, the mere 3% bonus you get for the 20 days (and more) of training it takes might not be worth it for them. However the 60% bonus you're missing if you don't train it plays a BIG role for the Skiff (we might even say the same for the Mackinaw).
Roughly, one unit of Mercoxit will refine into two units of Morphite, and at the time of release of this guide, one unit of Morphite goes for around 15 000 ISK/unit give or take. So we do the math and end up at a ISK/hour ratio of 49,200,000.00 ISK/hour. It's definitely not bad, especially for such a cheap ship (20mil ISK in Jita at the time of release of this guide).
Section 12 has a good comparative chart of the ISK/hour ratios you can get depending of what you mine and what you're flying. You'll see that Mercoxit, althought it isn't the flavor of the month anymore, doesn't do so bad at all!
This ends our section on Mercoxit. As you noticed I did not talk about mining Mercoxit in a battleship, simply because you cannot do so without mining crystals, and anyone serious enough about mining that trained for crystals will also have done so for mining barges.