1. Quartz mining predominated but there was some placer mining as well.2. In 1860 the Croydon Reef was discovered and quartz mining commenced. 3. Later Ophir became the center of quartz mining in the county. 4. Another major mine is The Sovereign Hill Quartz Mine which produces quartz. 5. With the prosperity brought by quartz mining , Sutter Creek became a boomtown. 6. San Jos?del Golfo has abundant natural resources, with traditional quartz mining . 7. The Sovereign Quartz Mine runs 40 minute guided tours and features several underground displays. 8. A silicon producer, Simcoa, has a quartz mine close to the town. 9. There was a dock with an advanced system for packaging and freezing fish, and several quartz mines . 10. Mining in Placerville began with placer workings for gold, but miners soon turned to quartz mining as well.
