Quartz

The use of quartz can be traced to ancient cultures. The Romans believed that quartz was permanently frozen ice because of the way it split light. Quartz, in its many varieties, is one of the most abundant minerals found on earth.

The electrical properties of quartz were discovered in the early 1900’s. By World War II, quartz crystals were used by the military to amplify radio signals. But because the US mined quartz in Brazil (one of the most abundant sources for various types of quartz crystals), the Germans realized they could just stop the ships coming to the US to halt American communications.

Scientists investigated ways to create synthetic quartz crystals (PDF format) in order to maintain use for communications. During the peak of the war, more than 125 factories cranked out synthetic quartz for the US military. Quartz crystals are made synthetically in the laboratory through a hydrothermal process. Today, most of the quartz crystals used are synthetically made. They are widely used as high-quality tuned circuits because they are cheap to produce and high in performance.