Dark orbit

"Reports of a strange, new habitable planet have reached the Twenty Planets of human civilization. When a team of scientists is assembled to investigate this world, exoethnologist Sara Callicot is recruited to keep an eye on an unstable crewmate. Thora was once a member of the interplanetary elite, but since her prophetic delusions helped mobilize a revolt on Orem, she's been banished to the farthest reaches of space, because of the risk that her very presence could revive unrest. Upon arrival, the team finds an extraordinary crystalline planet, laden with dark matter. Then a crew member is murdered and Thora mysteriously disappears"--Provided by publisher.