Quartz - The Sunless World, #1

A sunless world. The lost Tower of Light. And the race to claim it. Rafe Grenfeld, diplomat and spy, has problems. He's just learned of the discovery of a legendary quartz pillar: his world's most precious resource. But his informer died before revealing its location, and Rafe's on the run in the hostile state of Blackstone. Once, quartz powered magical devices, but the mages who created them are long gone.
Now, veins of quartz give light to a dying world, and Rafe has competition. Karzov, the notorious chief of Blackstone's secret police, is also hunting for the pillar. Determined to claim it for his own country, Rafe forms an uneasy alliance with the mysterious and maddening Isabella. As dangerous magical artifacts resurface and dark forces close in, Rafe must tap into the lost powers of the mages to find and secure the quartz-before his world is torn apart by famine and war.