The Mineral Resources of Texas map is designed to illustrate the historical and current (as of 1976) distribution of industrial mineral occurrences and production sites in Texas. Distributions of major rock types used in the mineral industry are also shown, including limestone, dolomite, ceramic clay, nonceramic clay, iron, sand and gravel, trap rock, granite, industrial sand, extrusive igneous rocks, talc, salt, and sulfur. The map also emphasizes the contribution that Texas makes to the National economy, reflecting Texas's position as one of the Nation's leading mineral producers.