Limestone is a sedimentary rock whose primary ingredient is calcium carbonate. Pure calcium carbonate is white, but limestone paving stones are often found in colors ranging from yellow to red to blue to steely gray and black, thanks to the inclusion of 'impurities' in the chemical composition of the stone.
What has all that got to do with your new patio floor or garden path? While the ancient Romans used crushed limestone as a basis for their roads, limestone has come to the surface in a big way in the last two centuries. Limestone paving materials are among the most popular natural stones used in creating outdoor paths and floors, taking their place alongside slate and sandstone. Limestone has a long history of use in construction. It was a popular choice for civic construction from the mid-1800s through the mid-1900s, and many railway stations and banks are faced with limestone and have floors and stairways made of limestone.
Limestone paving tiles and stones is durable underfoot, but is soft enough to cut easily with saws and hand tools. The natural striations and coloring variances can be enhanced by the cutting and finishing methods, making limestone paving materials a versatile and beautiful stone for building. Limestone is quarried throughout Europe, the United States, India and China. Because of its prevalence in 18th and 19th century building, some of the most beautiful varieties found as reclaimed paving stones and stone materials - much of it unique as it was quarried locally in small quarries that only supplied the stone for one or two projects.
Part of the reason for the popularity of limestone is the ease with which it can be cut and shaped. Because of that ease, it's often used as kerbing and edging for other stones. Limestone is available as larger blocks, slabs and strips that can be used for steps and slab flooring, or in setts and cobbles for patterned and cobbled walkways.
For an idea of how lovely and versatile limestone paving and tiles can be, imagine the subtle, understated drama of a circular pattern of blue limestone paving cobbles filled with black sand, or the striking visual impression of a border of inky black limestone cobbles around a mosaic floor of small white limestone paving cubes. Because limestone can take and retain a high polish, it's a popular choice for lower traffic areas where a mirror-like sheen is desired.
Limestone does require a bit more care than other stone paving products, especially if it has a polished finish. The organic calcium composition makes it vulnerable to acid rain which can stain and dissolve it. If acid rain is a concern in your area, your limestone patio will benefit from an awning to protect it.
Limestone paving sets can also be used to create walkways and retaining walls that are as beautiful as they are functional. Because the stone is easy to work, you can often have manufacturers custom cut limestone for specific accents in the shape of pillars, kerbstones and raised or patterned borders and edgings.