The Big Mine at Crested Butte (along with some of the other mines in that area, I believe) produced a lot of anthracite. At the time, I believe it was the largest anthracite producer in the U.S. outside of Pennsylvania. The mine west of Redstone also produced anthracite, while the mines on the North Fork of the Gunnison all produced (and continue to produce) a very good grade of bituminous. I would assume that coal from Hesperus is also pretty good bituminous.
Important grading considerations for coal are moisture content, ash, BTUS's per ton, and--these days--sulfur content. As an example, North Fork coal is high BTU, low ash, low moisture, low sulfur coal. It's extremely good coal, but is all underground mined--which is a costly proposition. Wyoming coal from the Powder River Basin also is low-sulfur, but has higher moisture and ash content, as is lower BTU. PRB coal is strip mined and is close to the surface, so it is relatively cheap to mine, making up for its "inferiority" to coal from some other sources.
Just as railroads designed their locomotives to utilize coal readily available to them, most new power plants are designed to burn coal from the source the utility plans to use for its coal. For many new plants, that is Wyoming PRB coal, and the plants are designed accordingly.
As an aside, modern coal mining is fascinating. I've had the opportunity to tour several working underground coal mines over the past several years (went over 5 miles into the mountain in one)--like railroading, it is a very high tech, mechanized operation these days. But, just like railroading is still railroading, coal mining is still coal mining, even with all the modern gadgetry. Going underground in a coal mine gives one a real appreciation of what it takes to get those BTU's out for us to use 'em! By the way, statistically, you are more likely to be injured or killed on the highway than is a modern coal miner working in a mine. One mine I know of posted a sign for its workers at the stop sign leaving the mine property at the state highway saying, "You are now about to start the most dangerous part of your day--Drive Carefully!"
