The Green Bone Saga #1 : Jade City book by Fonda Lee

The Kaul family is one of two crime syndicates that control the island of Kekon. It's the only place in the world that produces rare magical jade, which grants those with the right training and heritage superhuman abilities.

The Green Bone clans of honorable jade-wearing warriors once protected the island from foreign invasion--but nowadays, in a bustling post-war metropolis full of fast cars and foreign money, Green Bone families like the Kauls are primarily involved in commerce, construction, and the everyday upkeep of the districts under their protection.

When the simmering tension between the Kauls and their greatest rivals erupts into open violence in the streets, the outcome of this clan war will determine the fate of all Green Bones and the future of Kekon itself.