What is slate?

Slate is a foliated metamorphic rock, created by the metamorphism of the sedimentary rock shale. Shale has a composition mainly of clay and fine quartz which form parallel layers once heat and pressure is applied to create slate. This parallel forming of the rock allows for ease of breakage along these planes, making it relatively easy to mine, but also easy to wear over time.

The colour of slate depends on its mineral composition and is mainly found in shades of gray and black, but can also be found in dark green or red. Typically the darker coloured slates are more compact and have less water absorption, making them more durable for outdoor and wet environments.

Slate is a popular material for many uses, such as exterior pavers and roofing shingles, textured tiles, billiards tables and dishware. Usually the material’s ability to cleave and layers to flake off is what attracts people to use this stone, it is important to remember that natural wear and tear along these layers is to be expected. Using mineral oil and pH neutral cleaners to regularly maintain this stone will help increase longevity.