What kind of stone is slate

Some minerals, such as quartz grains, are flattened and stretched, while clay minerals are recrystallised as platy minerals: white mica and chlorite. The quartz minerals give the slate strength and durability, while the platy minerals form cleavage planes, which do not correspond to the bedding planes, but which allow the rock to be split into much thinner slabs suitable as roofing material. Differences in the composition of the original mudstone and the degree of metamorphism affect the quality of the slates thus produced.

Slate has a long tradition as a construction material. Slate is a natural, aesthetically pleasing stone. Its strength and outstanding resilience make it one of the most durable and versatile roofing materials. The beauty of slate lies in the fact that it is a natural resource that requires little alteration from its natural form and offers a long lasting, pollutant resistant, fireproof, waterproof material with a warmth and elegance which places it in a league of its own.

The age of the slate stone varies depending on the regional geology. For example in Scotland, Ballachulish slate was formed from sediments laid down approximately million years ago and was metamorphosed million years ago, while Spanish slate from the Orense area was formed from muds laid down over million years ago and was metamorphosed — million years ago. Slate is a fine-grained, foliated metamorphic rock that is created by the alteration of shale or mudstone by low-grade regional metamorphism.

The specimen shown above is about two inches five centimeters across. It is popular for a wide variety of uses such as roofing, flooring, and flagging because of its durability and attractive appearance. Slate is composed mainly of clay minerals or micas, depending upon the degree of metamorphism to which it has been subjected.

The original clay minerals in shale alter to micas with increasing levels of heat and pressure. Slate can also contain abundant quartz and small amounts of feldspar , calcite , pyrite , hematite , and other minerals. Slate roof: Most of the slate mined throughout the world is used to produce roofing slates.

Slate performs well in this application because it can be cut into thin sheets, absorbs minimal moisture, and stands up well in contact with freezing water. A disadvantage is the cost of the slate and its installation in comparison with other roofing materials.

As a result, in new construction slate is mainly confined to high-end projects and prestige architecture. Most slates are gray in color and range in a continuum of shades from light to dark gray. Slate also occurs in shades of green, red, black, purple, and brown.

The color of slate is often determined by the amount and type of iron and organic material that are present in the rock. The best way to learn about rocks is to have specimens available for testing and examination. The tectonic environment for producing slate is usually a former sedimentary basin that becomes involved in a convergent plate boundary. Shales and mudstones in that basin are compressed by horizontal forces with minor heating.

These forces and heat modify the clay minerals in the shale and mudstone. Foliation develops at right angles to the compressive forces of the convergent plate boundary to yield a vertical foliation that usually crosses the bedding planes that existed in the shale. School slate: School slate used for writing practice and arithmetic. Students wrote on the slate with a "pencil" made from slate, soapstone , or clay.

These slates were widely used until the late s, when wood-case pencils were easily produced and the price of paper became affordable. The word "slate" has not been used consistently over time and in some industries.

It also absorbs minimal water absorption index being 0. It is also favored for its resistance to moisture and good insulating capability.

Roofs made of slate can last for hundreds of years. However, slate is quite more expensive than other available roofing materials, and its installation cost more as well. Hence, the use of slate in the more recent times has been mainly restricted to high-end projects and prestige architecture. Slate is also used for outdoor and indoor flooring, and cladding. Floorings of porches, basements, bathrooms, and kitchens, can be made of slate. They are very durable, elegant-looking, and require less maintenance.

Some slates that are used for indoor flooring have a wide variety of finishes, patterns, shapes, and colors. Landscaping also make use of slate rocks, taking advantage of its resistant property to weather and pollution. Pavements, swimming pools, patios, and even contemporary fountains make use of slate either as a primary material or decorative stone.

Slate can also be used as billiard table tops, commemorative tablets, and tombstones. Home Everything you need to know about Slate Everything you need to know about Slate. Slate is considered as the finest grained foliated metamorphic rock.

Metamorphic rocks are formed from the change in form of existing rocks, a process called metamorphism. Slate arises from the repetitive layering or foliation of metamorphic rocks, particularly through the low-grade metamorphism of shale or mudstone. It is widely used in building roofs and floors, for it being fireproof and a good electrical insulator. It has also been popular in the use for billiard table tops, blackboards, tombstones, and commemorative tablets. It is widely used as a roofing material because of its low water absorption index of less than 0.

Slate is derived from shale-type sedimentary rock of clay or volcanic ash that underwent low-grade regional metamorphism. It is mainly composed of quartz and muscovite or illite. Some minerals like biotite, chlorite, hematite, and pyrite are also usually present in slate.

Apatite, graphite, kaolinite, magnetite, tourmaline, and feldspar are sometimes present as well, although less frequently. Some compound mineral can also be found in slate. This includes aluminum oxide, iron oxide, potassium oxide, magnesium oxide, sodium oxide, silicone dioxide, and titanium dioxide. The color of slate is determined by its mineral composition. Slates usually range from shades of light to dark grey in color. However, in some areas of slate industry such as in the town of Granville in New York, colored slate can be obtained.

It can occur in various shades of green, red, black, purple, and brown. If hematite is abundant, a slate is usually reddish in color.

Chlorite produces green slate, while sericite produces bluish-grey slate. Carbonaceuous materials make slate appear darker grey or black, while limonite makes it yellowish-brown. Slate is formed through the regional metamorphosis of mudstone or shale under low-pressure conditions.

When shale or mudstone is exposed to heavy pressure and heat from a tectonic plate activity, its clay mineral components metamorphose into mica minerals.