Definition of Porphyroblasts. Meaning of Porphyroblasts. Synonyms of Porphyroblasts

- A porphyroblast is a large mineral crystal in a metamorphic rock which has grown within the finer grained matrix. Porphyroblasts are commonly euhedral...
- schistosity. Though not a defining characteristic, schists very often contain porphyroblasts (individual crystals of unusual size) of distinctive minerals, such...
- local influences. This is a megascopic version of what may occur around porphyroblasts. Often, fine observation of foliations on outcrop, hand specimen and...
- characterized by co****, irregular grains, including some larger grains (porphyroblasts). In the United States, formations of quartzite can be found in some...
- loops revealing the metamorphic history of the rocks. Different porphyroblasts like garnet and quartz are often formed during metamorphism in different...
- megaphenocrysts. In metamorphic rocks, crystals similar to phenocrysts are called porphyroblasts. Phenocrysts are more often found in the lighter (higher silica) igneous...
- metamorphic rock characterized by an abundance of platy minerals. In this example, the rock has prominent sillimanite porphyroblasts as large as 3 cm (1.2 in)....
- may have been phenocrysts or porphyroblasts in the original rock. Porphyroclasts are often confused with porphyroblasts. The latter are also large crystals...
- be determined by the unaided eye, there are often larger crystals (porphyroblasts) of cordierite, garnet or andalusite scattered through the fine matrix...
- staurolite crystals are of prismatic shape. The mineral often forms porphyroblasts. In thin sections staurolite is commonly twinned and shows lower first...