Phyllite does not have any important industrial uses. It is not strong enough to serve well as a crushed stone. However, slabs of phyllite are occasionally trimmed and used as landscape, paving or sidewalk stone. Phyllite can provide valuable information about the geologic conditions that a geographic area or a rock mass was subjected to in…

Phyllite is composed mainly of tiny grains of mica minerals such as muscovite, or sericite. Fine-grained quartz and feldspar are often abundant in phyllite. These mineral grains are usually smaller than what can be easily seen with the unaided eye. They form through the low-grade metamorphic transformation of clay minerals. Crystals of other metamorphic minerals such as andalusite, biotite, cordierite, garnet, and staurolite might also form…

Phyllite was originally a fine-grained sedimentary rock such as shale or mudstone, composed mainly of clay minerals in a semi-random orientation. The rock was then buried and subjected to enough directed pressure to move the clay mineral grains towards parallel alignment, and enough heat and chemical activity to begin transforming the clay mineral grains into chlorite or a mica…

Phyllite is a foliated metamorphic rock that has been subjected to low levels of heat, pressure and chemical activity. It is composed mainly of flake-shaped mica minerals in parallel alignment. The strong parallel alignment of the mica grains allows the rock to be easily split into sheets or slabs. The alignment of the mica grains gives phyllite a reflective sheen…