Blaus is worth more than lyst and generally sells in auction for around 120-130% but if you hold out i think it will go up now that its needed for furniture crafting. I could be wrong but furniture is selling for a good profit and i think since blaus is an importnat part it will go up
Well at least you found something! I've never really done mining - I'll try it one day but I think you typically are meant to go for 100 bombs at a time and see how it works out for you.
Wistrel is right you need to take 100 bombs at a time at least then when you calculate your losses it will be much less (sometimes you'll even make a profit)
Mining is all about the area when you find a good area go back to it every 3 days or so and mine it again and you will usually find new deposits