PG Exam Workshop: Petrology and Petrography

Zoom presentation. Contact Ben Black at [email protected] for login information (AGS membership required)

Course Syllabus: This review will cover petrography and petrology relevant to minerals and rocks. Emphasize will be on facts and calculations that are likely to be presented in the ASBOG Exam. The petrography review will focus upon the microscope tools and microscope methods used by geologists to perform their duties. The primary focus will be on reflected light (RL) and polarized light microscopes (PLM), ubiquitous in classic geology departments, but often optional in departments that emphasize groundwater and environmental geology. The petrology review will cover the classification and origin of igneous, metamorphic, and sedimentary rocks, including coal. I will discuss field and laboratory classifications based upon color, grain size, and mineral content.
After discussing the tools and methods of petrography, we will review mineralogy and then mineral identification with a microscope. The major chemical and crystal classes of minerals will be covered, followed by their diagnostic features and associations. Then, the characteristic features of minerals in thin section will be presented. This will include crystal shapes, pleochroism, birefringence, twinning, and associated and alteration minerals. The IUGS classification schemes for plutonic and volcanic rocks will be described including QAPF diagrams. Bowen’s reaction series will be covered as will phase equilibria. For metamorphic rocks, the fabric, composition, and mineral facies schemes and their applications will be presented. Sediments and sedimentary rocks will be subdivided into quartz and silicate-rich sediments and rocks, carbonate sediments and rocks (limestones and dolomites), carbonaceous sediments and rocks (peat, lignite, bituminous coal, etc.), and other, less-common, rock types. The identification of heavy minerals will be presented, as will grain size, roundness, and texture analysis analyses of sediment grains. The relationship of Goldich’s dissolution series and Bowen’s series will be explained, and how Goldich’s observations explain the chemical and mineral composition of sedimentary rocks, especially arenites through lutites. For carbonate rocks, the highlights of the distinctions between limestones and dolomites will be covered, as will carbonate rock classification schemes, especially Folk’s particle type and texture classification. For carbonaceous sediments, we will discuss the characteristics of peat through anthracite.

Instructor: Steven Stokowski, CPG, is the owner and materials geologist of Stone Products Consultants. Steve’s primary professional interests are aggregates and concrete petrography. Steve has extensive geological and petrographic experience across the US. He has a MS in Geology from the South Dakota School of Mines and Technology and a BS in Geology from George Washington University. Steve is the Treasurer of the AIPG Atlanta Section, the 2014 recipient of the Herbert C. Hoover Award from the Washington DC Section of the Society for Mining, Metallurgy and Exploration (SME), the 2017 Robert W. Piekarz Award from SME, and the past Chair of the Industrial Minerals and Aggregates Division of SME. He is Registered or Certified as a Geologist in Georgia, Indiana, Maine, Virginia and other states.