Slate is a metamorphic rock formed by shale-like sedimentary rocks made of clay or volcanic ash. According to Geology.com, slate is a fine-grained and layered rock that has many uses in construction because of its durability and appearance. Like other metamorphic rocks, slate’s physical and chemical properties vary according to its location and the materials used to make it. The composition of slate makes it one of the natural materials used in different industries.
How Slate is Formed
Slate is formed when tectonic plated collide and cause intense pressure. The Mineral Information Institute says that metamorphism, or changes in the rocks, occur in different grades depending on the amount of pressure and heat exerted on the rock. The institute says, “Slate represents low-grade metamorphism of shale. As the pressure increases, the grade of metamorphism increases through a series of different rock types. With increased metamorphism the crystals in the rock become larger.” The fine grains in slate are invisible to the naked eye.
Composition and Color
Slate usually occurs in various shades of gray, but it also appears in green, red, black, purple and brown. Geology.com says the different colors found in slate depend on the amount of iron and organic materials in the rocks. In addition to clay and volcanic materials, slate contains quartz, feldspar, calcite, pyrite, and hematite. The variety of colors gives it qualities that change the appearance of what it’s used to make. Though slate contains finely-graded materials, it is actually strong and durable.
Where to Find Slate
You can find slate in different regions all over the world. Some of the largest concentrations lie in the United States. According to the Mineral Information Institute, an area nicknamed the Slate Belt is located in eastern Pennsylvania in the Appalachian Mountains. Another area of the United States called the Slate Valley sits between Vermont and the eastern part of New York State. Slate can be found internationally in Great Britain, Italy, Portugal, Germany, Brazil and China. Basically, you can find slate on almost every continent.
How Slate is Used
Society has relied on slate for centuries for items as varies as tombstones, whetstones, table tops, billiard tables, blackboards and writing slates once used by school children. The construction industry uses slate materials for roofing materials, flooring and paving. Interestingly, parts of turkey calls contain some slate, according to Geology.com.
Conclusion
A combination of chemical processes and pressure determines the composition of slate rocks. The metamorphosis that it goes through determines the look and feel of the rocks, thus making it one of the most versatile materials used. Because of its ability to transform, slate has been used for centuries for a variety of items. Slate’s versatility will likely continue being used as other uses are discovered.
