The Arch Stone by Adam Faulkner (Foxway Academy #1)

17-year-old Emilie George had always known she was adopted. She'd been told at an early age, she'd never really cared. Her mother was her mother, and she'd never had any desire to change that. But, despite this, she always felt that something in her life was missing, something which wasn't quite right. Emilie George knew she was supposed to have a sister. Until one February evening, when Emilie is attacked by a man who can create earthquakes, and is saved by a stranger who, other than her jet black hair and burning red eyes, looks exactly like her. As she gets to know her long-lost twin, the mysterious Raven Blake, Emilie enrolls at the Foxway Academy beginning to and begins to learn the basics of Magic.

But as a powerful and mysterious Magical artefact comes into Emilie's possession, she discovers that the responsibilities it brings are far from safe. When the object's appearance puts Foxway under threat from the ruthless Syndicate, Taught by the school's enigmatic headmaster Maximillion Greyford, and alongside Raven, as well as the eccentric Silvemist twins and the hot-headed August Flamel, Emilie begins to train, in magic and in fighting, to prepare for the fight ahead.

But with the Syndicate's forces being led by an extremely powerful and even more dangerous Magical, with a strong connection to Raven, Emilie finds that this new world is more dangerous than she could ever have imagined.