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Slate is rock used for many purposes, such as gardening boundaries, decorative paths, roadways, memorial tablets, electrical insulation and roofing materials. A form of flagstone, slate is broken down into smaller pieces to produce slate gravel. The different types of slate gravel can be categorized according to color and the size of the pieces. Slate gravel is primarily a gray color but there also are green, pink and red types, with many variations in between. Slate gravel can be purchased from suppliers in different sizes and is commonly found in diameters of 0.75 inches (20 mm), 1.5 inches (40 mm) and 3 inches (75 mm).
Gravel made of slate is often used for driveways instead of traditional gravel as a method to reduce noise when vehicles travel on the surface. This type of gravel is known to produce less noise than other types of gravel when a car is driving on it or someone is walking on it. Slate gravel is very resistant to weather conditions such as frost and freezing, which is why slate is a viable and common roofing material. It also absorbs very little water, thus making the material highly desired for many purposes.
Quarries or mines that produce slate are located in regions of the United Kingdom, Spain, Italy, Germany, the eastern United States, Portugal and Brazil. Slate is a metamorphic rick that is originally known as shale. Over time, shale becomes buried deep under ground. As pressure and heat builds, the shale begins to transform into slate.
Slate can be distinguished from similar rocks by a few basic characteristics. It is commonly known by its colors and breakage pattern. When struck against an object, larger pieces of slate will break in flat pieces. Slate is known to be shiny or silky when in direct sunlight and can be scraped into a powder with a sharp object. Other common characteristic include wavy patterns, embedded crystals that make small lumps and white streaks called “veins” that are made of minerals such as calcite and quartz.