I'm reading an ARC of David Walton's
Quintessence, which comes out from Tor this month. It's a much better book than the cover art would have led me to believe. A nice blend of historical accuracy, creepy weird dark magic, and human innovation.
The Amazon description leaves out some of the more interesting aspects of the book, including the King of England's physician, Parris, who is discovered dissecting dead bodies and forced to join the expedition (along with his scientifically inquisitive daughter). Also, there are magical creatures able to become insubstantial at will, and a boat of mysteriously dead explorers right at the book's outset.
[Disclosure: David's a longtime friend of mine, and I'm predisposed to like his books. On the other hand, this one kept me up way past bedtime, which is always a sign of good writing.]