The Machinations of Angels by Christopher McAfee

Angels have more of humanity in them than divinity. This is a truth I learned the hard way. I met my first angel when Nauvoo, the city of Joseph, was near the height of its glory. Visitors to Nauvoo in 1846 could witness a good many wonders of industry and innovation. Inside the city, people would see steam-driven wagons and armored carriages speeding around on concrete roads. On the Mississippi River, people might see our metal-plated steamboat or, more likely, quick moving river runners pushing upstream at exceptional speed. These technological marvels and more gave Nauvoo a reputation for being unassailable and, despite hatred that emanated inwards from surrounding communities, nobody dared come against the city. While the rumor that we had an arsenal to match our other inventions was only partly true, we chose not to contradict that particular rumor.

Two things made this possible: the copper mine and the coal mine. Well, those and the intuition of Joseph Smith. He had a way of divining where things could be found. He found the coal deposits just outside Nauvoo while out exploring with a small party of men. As the story goes, he stopped suddenly at the side of a hill and said, "There's coal here. Get some shovels! " Within a day, they found the coal mine. Incredibly, he found the copper mine just one week later. He sent a party down the Mississippi river with an exact description of the copper mine's location. They found it down the river a ways on the Missouri side, just as described. So it was that we had coal to drive our steam-powered machines and copper to share electricity throughout the city