Yorkstone or York stone is a variety of sandstone, specifically from quarries in Yorkshire that have been worked since mediaeval times. Yorkstone is a tight grained, Carboniferous sedimentary rock. The stone consists of quartz, mica, feldspar, clay and iron oxides.
The ratio of quartz to mica varies considerably. The stone can be split along mica-rich layers: it has a slaty cleavage and may therefore be called sandstone slate. Formerly riven (split with a chisel along the bedding planes between the sedimentary layers), it is now also often sawn. It is used for flagstones and for building walls.
Known for its hard-wearing and durable qualities, Yorkstone has been used in a wide array of building, construction and landscaping applications around the world for many years. In Yorkshire, split stones called thackstone (Scots thack, English thatch) were employed as roofing. The traditional London paving stone has been cut and pressed from quarries in Holmfirth, West Yorkshire. Yorkshire Stone is most commonly used for paving and garden walls, but it is also a popular choice for new builds as well as home extensions and conversions due to its durability to harsh weather conditions.
The colour of Yorkstone depends on the minerals within its makeup and differs throughout the quarries from which it is mined. It also depends on the age of the stone and turns darker with weathering. Newly quarried Yorkstone is available as slabs for paving, setts and walling stones. It is also available to buy from stonemasons as a custom-shaped product such as signage.
Reused Yorkstone paving, salvaged from demolished sites, is valued for its naturally weathered surfaces. Both old and new Yorkshire Stone can be used for paving and building alike. Reclaimed Yorkshire stone is becoming more popular for its colouring and also for environmentally friendly builds. Most stone companies in Yorkshire will cut the stone to 140mm walling size and offer a colour matching service for home extension projects.
Yorkstone often shows features such as laminations with cross bedding, and rusty Liesegang bands.
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The true Sandstone Slate has commonly intermixed with it Mica, by which it is also generally traversed on its slaty fracture, as in the English Yorkstone, Bremingstone, &c. The proportion of Quartz to Mica, however, varies considerably as well with regard to the quantity as to the distribution.