<descriptor thcode="4"><thesaurus thcode="4" name="Lithologic classification of geologic map units" scope="Rock types commonly found on geologic maps. Terms may combine compositional, textural, and genetic characteristics. Also includes unconsolidated materials that may be mapped as units. Not specific enough for categorizing hand samples or outcrops." creator="U.S. Geological Survey" rights="Public domain" edition="6.2" date="2004-08-16" codetype="alpha" prefix="lithclass" uri="http://www.usgs.gov/science/Lithclass6.2" tblname="lith" nonpref="lithnp" relterm="lithrt" root_code="0" contact="pschweitzer"><category><term thcode="25" code="10" name="persons" parent="2" scope="Terms specify individual people, typically by name."/><term thcode="25" code="30" name="ambiguous labels" parent="26" scope="A given preferred label may be used for more than one concept in the thesaurus. A concept must be specified using its unique identifier (code). This may occur in the names of places or people."/><term thcode="25" code="17" name="pseudohierarchical" parent="11" scope="Broader-narrower relationships exist in the vocabulary but have no semantic relation to the terms themselves, for example, a list of peoples' names arranged hierarchically by the first letter of the surname."/><term thcode="25" code="14" name="not transitive" parent="12" scope="Narrower terms cannot reliably be understood as parts of, types of, or instances of the terms that are broader than them."/><term thcode="25" code="9" name="organizations" parent="2" scope="Terms specify human organizations, their subdivisions and relationships, as well as characteristics of such organizations."/><term thcode="25" code="10" name="persons" parent="2" scope="Terms specify individual people, typically by name."/><term thcode="25" code="30" name="ambiguous labels" parent="26" scope="A given preferred label may be used for more than one concept in the thesaurus. A concept must be specified using its unique identifier (code). This may occur in the names of places or people."/><term thcode="25" code="17" name="pseudohierarchical" parent="11" scope="Broader-narrower relationships exist in the vocabulary but have no semantic relation to the terms themselves, for example, a list of peoples' names arranged hierarchically by the first letter of the surname."/><term thcode="25" code="14" name="not transitive" parent="12" scope="Narrower terms cannot reliably be understood as parts of, types of, or instances of the terms that are broader than them."/><term thcode="25" code="9" name="organizations" parent="2" scope="Terms specify human organizations, their subdivisions and relationships, as well as characteristics of such organizations."/></category><altlabel><altlabel>Lithclass6.2</altlabel><altlabel>Lithclass6.2</altlabel></altlabel></thesaurus><term thcode="4" 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."/><bt><term thcode="4" code="0" name="Earth material" scope="Geologic map unit classification (Bruce R. Johnson) version 6.2: A hierarchical classification of earth materials for digital geologic maps."/></bt><nt><term thcode="4" 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."/><term thcode="4" code="4.1" name="Aplite" parent="4" scope="A light-colored igneous rock characterized by a fine-grained allotriomorphic-granular (i.e. aplitic) texture."/><term thcode="4" code="4.5" name="Gabbroid" parent="4" scope="A plutonic rock with Q &lt; 20% or F &lt; 10%, P/(A+P) &gt; 65%, and pl/(pl+px+ol) between 10 and 90%."/><term thcode="4" code="4.4" name="Granitoid" parent="4" scope="A general term for all phaneritic igneous rocks dominated by quartz and feldspars."/><term thcode="4" code="4.8" name="Intrusive carbonatite" parent="4" scope="A plutonic rock composed of at least 50% carbonate minerals."/><term thcode="4" code="4.3" name="Pegmatite" parent="4" scope="An exceptionally coarse-grained igneous rock, with interlocking crystals, usually found as irregular dikes, lenses, or veins, esp. at the margins of batholiths."/><term thcode="4" code="4.2" name="Porphyry" parent="4" scope="An igneous rock of any composition that contains conspicuous phenocrysts in a fine-grained groundmass."/><term thcode="4" code="4.7" name="Ultramafic intrusive rock" parent="4" scope="A general name for plutonic rock with color index (M) greater than or equal to 90..."/></nt></descriptor>