Quartzite is a non-foliated metamorphic rock composed in its majority of quartz, and formed from the sedimentary rock sandstone. A metamorphic rock is formed when constituent minerals recrystallize in a new molecular arrangement due to tectonic compression and heating. Quartzite is transformed from, its protolith or parent rock, sandstone. Quartzite shows a glassy luster and a gray to white color; however, it can acquire other light colors based on the impurities present in its parent rock. The physical properties of quartzite, including toughness and density, make this metamorphic stone particularly resistant to erosion and weathering.
Metamorphism
Metamorphism is the geological process by which igneous and sedimentary rocks are transformed into other types of rocks with different physical characteristic. The parent rock (protolith) is subjected to the internal forces of the Earth, including heat and pressure. This produces dramatically physical and chemical changes in the original rock. This usually occurs in sedimentary and igneous rocks. The mineral components are subjected to extreme pressure and heat, causing a rearrangement of their mineral components in new directions which give them a new physical appearance. Through metamorphosis, many rocks are transformed, for instance, shale transforms into slate, limestone into marble and sandstone into quartzite.
How is quartzite metamorphosed?
Quartzite is metamorphosed in two distinct ways. In the first, sandstone minerals recrystallize under the influence of extreme temperatures and pressures due to deep burial. Through this process, quartzite does not conserve traces of its protolith’s original grains and its sedimentary structures are erased. When this occurs, quartzite is known as a metaquartzite. In the second, circulating fluid fills empty spaces in between sand grains with silica, although the orthoquartzise, as it is called, preserves the original mineral grains and other sedimentary structures, therefore, it is considered a sedimentary rock in origin. This stems from the cementation of quartz sandstone by ground water solutions of pure quartz.
Where is quartzite used?
Quartzite is utilized in the construction industry. The use of quartzite as decorative material in construction is becoming somewhat popular. When quartzite is broken, its surface remains flat, therefore, quartzite slabs are used to decorate floors, stair steps, in walls, roofing tiles, and the manufacture of kitchen countertops, among many other decorative uses. Quartzite, as crushed stone, is also used in road construction and repair. Due to its hard surface and angular shape, quartzite is used as a stone for stabilization (ballast) along the railroad tracks. When quartzite is packed in between the rails and ties, it facilitates drainage and prevent the growing of vegetation. Quartzite has not been used extensively, as other softer stones; however, it is estimated that if its demand grows, its utilization could increase in the near future.
Where is quartzite found?
Quartzite can be found in regions of high-pressure metamorphism, especially in mountainous regions, where the continental plates collide with each other, causing the formation of new mountainous formations. They can form where the forces of temperature and pressure, due to the rearrangement of tectonic plates, combine to metamorphose existing sandstone deposits. In the U.S., it can be found in the Appalachian Mountains, southwest Minnesota, Salt Lake City, Utah, central Texas, Arizona and Idaho. Quartzite is highly resistant to chemical weathering and usually forms in ridges and resistant hilltops where it can be seen covered with a thin layer of soil and little vegetation.
The durability and characteristic texture of quartzite makes it a popular stone in the construction industry. Both contractors and home owners are making from quartzite one of their preferred stones for decorative purposes. The construction materials created from quartzite include ceramic tiles, resin-agglomerated stone, concrete, bricks, among others. According to ephemeral.com, quartzite possesses compacted well-formed grains of clear to cloudy quartz, and is highly strong. Quartzite is the raw material in the ceramic and glass industries.
