Intrusive contacts are the surfaces between the surrounding country rock and an intrusive magmatic body that cools after the intrusion. The edge of the intrusive rock mass contains fine crystalline minerals due to the rapid cooling and forms a chilled margin. The country rock responds to the high heat and fluid dynamics from the intruding magma to form a contact metamorphic zone by recrystallization. The primary flow surface structure of the rock mass is consistent with the contact surface. Intrusive contacts are important evidence for determining whether a rock mass is an intrusive body and to identify the sequence of intrusion.