The matrix or groundmass of rock is the fine-grained mass of material in which larger grains or crystals are embedded. Sedimentary, volcanic, plutonic, metamorphic rock types of North America. ... It has been suggested that crystallization processes be merged into this article or section. ...

The matrix of an igneous rock consists of fine-grained, often microscopic, crystals in which larger crystals (phenocrysts) are embedded. This porphyritic texture is indicative of multi-stage cooling of magma. For example, porphyritic andesite will have large phenocrysts of plagioclase in a fine-grained matrix. Also in South Africa, diamonds are often mined from a matrix of weathered clay-like rock (kimberlite) called "yellow ground." Volcanic rock on North America Plutonic rock on North America Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Example of phenocrysts in rhomb porphyry from the Oslo rift area in Norway A phenocryst is a relatively large and usually conspicuous crystal formed in the mass of a porphyritic igneous rock. ... (For other meanings of Porphyr, see Porphyry) A slab of imperial porphyry from Egypt, about 15 cm across. ... Magma is molten rock located beneath the surface of the Earth (or any other rocky planet), and which often collects in a magma chamber. ... A sample of andesite (dark groundmass) with amygdaloidal vesicules filled with zeolite. ... Lunar Ferroan Anorthosite #60025 (Plagioclase Feldspar). ... For other uses, including the shape â—Š, see Diamond (disambiguation). ... Weathered is an album by Creed, released on November 20, 2001. ... The Gay Head cliffs in Marthas Vineyard are made almost entirely of natural clays. ... Hewn kimberlite core sample from the James Bay Lowlands region of Northern Ontario, Canada. ...

The matrix of sedimentary rocks is a fine-grained clay or silt in which larger grains are embedded. Two types of sedimentary rock: limey shale overlaid by limestone. ... Silt refers to soil or rock particles of a certain very small size range (see grain size). ...