The most common sedimentary rock is shale. It is made of compressed mud–that is, a mixture of clay and silt (fine particles of mineral matter). Shale is used in making bricks. Limestone, another common sedimentary rock, is made chiefly of the mineral calcite.

Construction Materials: Dimension Stone The slate group consists of slate and shale. Slate is a microcrystalline metamorphic rock, most often derived from shale and composed mostly of micas and quartz. Shale is a fine-grained laminated sedimentary rock composed of silt and clay-sized particles.

Sand and gravel for construction come from sediment. Sandstone and limestone are used for building stone. Rock gypsum is used to make plaster. Limestone is used to make cement.

Most schists are composed largely of platy minerals such as muscovite, chlorite, talc, sericite, biotite, and graphite; feldspar and quartz are much less abundant in schist than in gneiss.

Schist Mine (Snake River Mine), Conner Creek District, Baker Co., Oregon, USA

metamorphic rock

It is used as paving stones and as a veneer or facing on buildings (both for interior and exterior use). It is also used as crushed stone for the usual crushed stone applications such as road and railroad bed construction. In this application it is used locally, near the source of the amphibolite.

The soft, clay-rich rock known as shale, when subjected to pressure becomes a harder rock called slate. Often, the changes are even more spectacular, with new minerals formed, such as garnet, mica, and tourmaline (as seen in schist). The heat causes a localized “baked zone” of metamorphosed rock.

Metamorphic Rocks

It becomes cemented together by chemical interactions and it becomes a sedimentary rock called shale. The shale is put under moderate pressure and low temperature due to burial or plate movements. The new pressure and temperatures changed the chemical make up of the shale into the metamorphic rock called slate.