The genesis of the Sullivan orebody is reviewed in terms of current concepts of stratiform ore formation. The source of metals and sulfur, the environment and time of ore formation, and the imprint of subsequent metamorphic events are explained in terms of a model which views the ore as one component of a chemical and clastic sequence formed within a rift basin above a thermal anomaly. Classic primary sedimentary structures are displayed in both the chemical (sulfide) and the clastic (silicate) rocks. Fractures and breccia zones beneath the western section of the mine provided passage-ways for boron and metal-rich sulfur-poor brines. Sulfides formed when the metals combined with reduced marine sulfur. The pattern of metal zoning is a reflection of the location of brine vents. The boron-rich solutions produced the tourmaline alteration zone. The sodium-rich brine produced albite within the ore sequence and in the hanging wall perhaps by the modification of analcite. The manganese variation of sulfide minerals between ore bands and laminations reflect changes in the chemistry of solutions during sedimentation and some degree of partitioning during metamorphism. The metamorphism has modified both the sulfide and silicate assemblages.