A category of stocks that accounts for companies involved with the discovery, development and processing of raw materials. The basic materials sector includes the mining and refining of metals, chemical producers and forestry products. Taobiz explains Basic Materials Sector The basic materials sector is sensitive to changes in the business cycle. Because the sector supplies materials for construction, it depends on a strong economy. This sector is also sensitive to supply and demand fluctuations because the price of raw materials, such as gold or other metals, is largely demand driven.