Drive along Highway 46 in central California, and you’ll be greeted by an expanse of more than 200 wineries in Paso Robles, a region known for mineral-rich soils, hot springs and vineyards that yield full-flavored wines of character. However, the area did not start as an agricultural gem. It was mercury mining that put Paso Robles on the map.
For more than 100 years, the Adelaida area, about 15 miles west of the city of Paso Robles, produced a bonanza of this metal, also known as “quicksilver.” Communities of miners and their families settled in the region from the mid-1800s through the early 1900s to extract this mineraloid. Mining companies built roads and infrastructure while families founded schools, post offices and farms that blossomed into the orchards and vineyards that dot the region today. You can still see the exhausted remnants of the mines tucked away between the region’s wineries, if you know where to look.
The first quicksilver mine in San Luis Obispo County was excavated on the southern edge of the Las Tablas area. The Josephine Quicksilver Mining Company was incorporated in 1864 to work a deposit of cinnabar. Also known as mercury sulfide, cinnabar is a reddish rock used since prehistoric times for its bright pigment. Liquid mercury was extracted from cinnabar onsite in furnaces near the mines.
The only metal that’s liquid at room temperature, mercury proved useful in many applications, from thermometers to barometers. But perhaps its most prized use at the time was for extracting gold and silver from ore deposites and stream sediments. During California’s gold rush days, easily accessible quicksilver was a valuable asset, and one that gave Paso Robles its early start.
The extraction of liquid mercury from cinnabar was intensive work that required large numbers of miners and machinists. To sustain these workers, an agricultural industry took hold alongside the mines.
Among the influx of new settlers to Paso Robles, some European immigrants noticed that the land’s rich soils and climate were similar to those of their home countries. They planted small vineyards that soon started producing wine.
In 1882, York Mountain Vineyard (now Epoch Estate Wines), opened, eventually becoming one of the first bonded wineries on the Central Coast. By the 1920s, vintners and vignerons like Frank Pesenti and Sylvester Dusi dry-farmed Zinfandel vines in the region. After Prohibition ended in 1933, these wineries opened for business. Early producers like York Mountain, Rotta and Pesenti (now Turley) were favorites among the mining families.
By the 1960s, owing to an increased awareness of the metal’s toxicity, most of Paso’s original mercury mines had closed, while the agriculture industry rose to take their place. The same mineral-rich soil that resulted in profitable mining also laid the foundation for renowned California wines.