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intrusive igneous rock of ultramafic (very silica-poor) composition that is composed largely of olivine and augite and is somewhat similar to peridotite. Picrites are dark, heavy rocks and contain a small but variable amount of plagioclase feldspar; hornblende and biotite may also be present. Picrites usually occur in sills (tabular bodies inserted while molten between other rocks), but, unlike peridotites, they seldom are found in large plutonic masses. Varieties include augite-, enstatite-, and hornblende-picrite. The term picrite-basalt is reserved for feldspar-poor basalts rich in olivine.