Item talk:Q41946

Mindat Description

Metamorphic rocks that have undergone a significant change in mineral and chemical bulk composition by metasomatism, eg

Geoscience Ontology Description

SLTTm (2004) proposed the following criteria to distinguish hydrothermally altered or metasomatic rock from igneous rock. "The rock is classified as metamorphic if (1) the texture has been modified such that it can no longer be considered igneous, (2) the bulk composition of the rock is inconsistent with compositions that can be derived purely from a magma and associated processes such as assimilation and differentiation, or (3) minerals inconsistent with magmatic crystallization are present." Rock that has fabric and composition indicating open-system mineralogical and chemical changes in response to interaction with a fluid phase, typically water rich.