Magma typically consists of (1) a liquid portion (often referred to as the melt); (2) a solid portion made of minerals that crystallized directly from the melt; (3) solid rocks incorporated into the magma from along the conduit or reservoir, called xenoliths or inclusions; and (4) dissolved gases.
Magma that cools and solidifies within the crust may form either plutonic (at great depths) or hypabyssal (at intermediate depths) rocks.
Large masses of magma are called batholiths, and thin seams of magma create sills and dikes.
Related category GEOLOGY AND PLANETARY SCIENCE
Source: U.S. Geological Survey
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