{"thcode":2,"term":{"code":880,"name":"petrography","parent":619,"scope":"Use of optical microscopy for the description and classification of rocks."},"uf":[{"name":"thin section analysis","usewith":false}],"bt":[{"code":619,"name":"laboratory methods","parent":734,"scope":"Techniques to analyze and test samples in a place equipped and designed for the work."},{"code":734,"name":"methods","parent":1,"scope":"Techniques, methods, procedures, or strategies for research, management, collection, or analysis of scientific information in USGS."},{"code":1,"name":"Categories","parent":null,"scope":"Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."}],"nt":[],"rt":[{"code":835,"name":"optical microscopy","parent":740,"scope":"Scientific techniques using a microscope with one or more lenses illuminated with visible light to view small objects."},{"code":883,"name":"petrology","parent":464,"scope":"Branch of earth sciences concerned with the origin, structure, alteration, and composition of rocks."},{"code":1005,"name":"rocks and deposits","parent":287,"scope":"Solid masses that make up the earth's crust as well as accumulations of materials. Use for major rock types and unconsolidated deposits. For deposits of economic value, see related terms."}]}