{"thcode":4,"term":{"code":"4.6.1","name":"Nepheline syenite","parent":"4.6","scope":"A plutonic rock defined in the QAPF diagram as having F\/(F+A+P) between 10 an 60%, and P\/(P+A) < 50%; composed essentially of alkali feldspar and nepheline..."},"uf":[],"bt":[{"code":"4.6","name":"Alkalic intrusive rock","parent":"4","scope":"A plutonic rock that contains more sodium and\/or potassium than is required to form feldspar with the available silica."},{"code":"4","name":"Plutonic rock","parent":"0","scope":"A rock formed at considerable depth by crystallization of magma and\/or by chemical alteration.  It is characteristically medium- to coarse-grained, of granitoid texture."},{"code":"0","name":"Earth material","parent":null,"scope":"Geologic map unit classification (Bruce R. Johnson) version 6.2: A hierarchical classification of earth materials for digital geologic maps."}],"nt":[],"rt":[]}