Sulphur Springs Mountain (or Sulfur Springs Mountain) is a mountain in southwestern Solano County, California. The slopes can be accessed via hiking trails emanating from Blue Rock Springs Park in the city of Vallejo. Cinnabar deposits were extracted from this location in the early 1900s at Hastings Mine and St. John's Mine. Both mines are classified as medium priority mine from the standpoint of environmental oversight for California inactive mines. The highest peak on Sulfur Springs Mountain stands at an elevation of 1,112 feet (339 m), and affords expansive views of the northern San Francisco Bay as well as the Napa River.