Cinnabar is generally formed near volcanic or hot spring activity. The mineral crystallizes when mercury combines with sulfur either from volcanic emissions or from sulfur-containing hot spring waters. The combination of heat and sulfur is required for cinnabar to form naturally.
Some major deposits of cinnabar occur in California, Nevada, Alaska, Turkey, Spain, Italy, Yugoslavia, and China. Several key areas where cinnabar forms naturally are:
- The California Coast Ranges: Cinnabar is abundant around the Clear Lake volcanic field and near New Idria in San Benito County, California. The New Idria Mine produced significant quantities of cinnabar for decades. The brilliant red rocks surrounding the Sulphur Bank Mine near Clearlake are famous for their vivid cinnabar hues.
- Southwest Oregon: Cinnabar mineralization is found near the Oregon Cascades around Silver Peak and in the Roseburg area. The historic Black Butte cinnabar mine was a notable producer.
- The Mayacamas Mountains region north of Napa/Sonoma, California contains cinnabar deposits near Geyser Peak and Mt. St. Helena. This was site of the famous Napa Consolidated mine.
- Islands off the coast of Sicily, Italy such as Pantelleria contain significant cinnabar associated with volcanic activity. Bright red cinnabar rocks can be found eroding along shorelines.
- The Zhushan-Tongren area of Guizhou Province, China contains important cinnabar deposits that have been mined for centuries. The brightly pigmented rocks are crushed to produce the brilliant vermillion powders.
- The Nikopol deposit in Ukraine contains rich cinnabar mineralization that has supplied pigments and mercury for many years.
- Parts of Yugoslavia such as near Belgrade and in southern Serbia have produced cinnabar historically.
- Areas of western Turkey such as near Diyarbakır host geologic deposits of cinnabar associated with young volcanic landscapes.
- The Almadén district of Spain was once one of the richest sources of cinnabar in the world. Spanish cinnabar was used globally for pigments from Roman times through the 19th century.
- Other countries with cinnabar deposits include parts of Russia, Peru, Mexico, and tiny occurrences are found sporadically near hot springs and volcanoes worldwide.
So, cinnabar generally requires a source of volcanism or hot springs to form. The mineral crystallizes readily when mercury and sulfur come together at elevated temperatures near vents or fumaroles. Historic mining of cinnabar has focused near young active geothermal systems in the Mediterranean, Americas, and Asia. Cinnabar's brilliant color has captivated artists and craftsmen for thousands of years and sources of the prized mercury ore have been highly sought after throughout history.
