Petrography : an introduction to the study of rocks in thin sections / Howel Williams, Francis J. Turner, Charles M. Gilbert. Williams, Howel, 1898- Turner, Francis J. Gilbert, Charles M., 1910- Petrology. Thin sections (Geology) QE434 .W73 1982 552 19 WIP Includes bibliographical references and indexes. San Francisco : W.H. Freeman, c1982. c1982. 1982 Text xiv, 626 p. : eng