Unit 10: Energy Challenges // Section 14: Other Material Resources
A wide variety of other material resources are extracted from geological deposits, including stone building materials, fertilizers, and industrial chemicals. Building stones, which are chosen for a combination of durability and aesthetic appeal, include marble, granite, limestone, slates, and sandstones. Aggregates such as crushed stone, gravel, and sand are also widely used for construction and to manufacture concrete and other treated rock products. Rock products are used directly as insulators, abrasives, and paint pigments and in many other applications.
Before the industrial era, farmers used manure and bone meal as fertilizers, but manufacturing fertilizer has become a major industry. As discussed in Unit 4, "Ecosystems," and Unit 7, "Agriculture," the primary elements of fertilizers are nitrogen, phosphorus, and potassium. Today potassium and phosphates are mined from ancient marine beds, while nitrogen is extracted from the air by burning natural gas to form ammonia (NH3).
Rocks and minerals also are used as feed stocks for a wide variety of industrial chemicals such as sulfuric acid, flame retardants, wood preservatives, glass, ceramics, paper coatings, and battery and computer chip components. Ore deposits for the raw materials to manufacture most of these products are generally plentiful, so the economics of extracting, processing, and transporting feed stocks generally dictates which materials are developed.