Rocks: Igneous, Metamorphic and Sedimentary

• Andesite.
• Basalt.
• Dacite.
• Diabase.
• Diorite.
• Gabbro.
• Granite.
• Obsidian.

Diorite, medium- to coarse-grained intrusive igneous rock that commonly is composed of about two-thirds plagioclase feldspar and one-third dark-coloured minerals, such as hornblende or biotite.

Diorite is an intrusive rock intermediate in composition between gabbro and granite. It is produced in volcanic arcs, and in mountain building where it can occur in large volumes as batholiths in the roots of mountains (e.g. Scotland, Norway).

Diorite is sodium-rich due to the high content of plagioclase. It has hornblende, biotite, and pyroxene minerals as minor content. Diorite has traces of other minerals found in other igneous rocks. The presence of quartz and feldspar gives it a contrasting black & white appearance.

foliated metamorphic rock

Phyllite is commonly found in the Dalradian metasediments of northwest Arran. In north Cornwall, there are Tredorn phyllites and Woolgarden phyllites….External links.

The alignment of the mica grains gives phyllite a reflective sheen that distinguishes it from slate, its metamorphic precursor or protolith. Phyllite is usually gray, black, or greenish in color and often weathers to a tan or brown. Its reflective sheen often gives it a silvery, nonmetallic appearance.

Metamorphic rocks composed primarily of amphibole, plagioclase, with subordinate epidote, zoisite, chlorite, quartz, titanite, and accessory leucoxene, ilmenite and magnetite which have a protolith of an igneous rock are known as Orthoamphibolite.

The protolith of slate is shale. Shales themselves are…

The type of rock that a metamorphic rock used to be, prior to metamorphism, is called the protolith. During metamorphism the mineral content and texture of the protolith are changed due to changes in the physical and chemical environment of the rock.

The original rock that has undergone metamorphism is called the protolith. Protolith can be any type of rock and sometimes the changes in texture and mineralogy are so dramatic that is difficult to distinguish what the protolith was.

What is the protolith of marble? Limestone. (A protolith is the parent rock that is metamorphosed into a different rock; metamorphosed limestone is marble.)

Based on its composition, natural stone has two general categories: Siliceous stone is composed mainly of silica, or quartz-like particles. These types of stones include marble, travertine, limestone, and onyx.

Black Marble The average cost for this type is $75 per square foot.