Natural stone refers to organic rock that is quarried from the earth and is used for building and decorative purposes. It is an organic solid composition made up of one or more minerals.
Variation
Because stone is a product of nature, no two pieces are the same and this is what makes natural stone beautifully unique. Variations could be in the stones colour, markings, shading, veining, texture movement or finish. Do not be alarmed that there are variations in your stone, these are not defects but beautiful characteristics that should be adored.
Types of natural stone:
Sandstone:
Sandstone is an arenaceous sedimentary rock predominantly composed of grains of silica. Depending upon the particle size which can vary from 60 micron to 2mm, sandstones are characterised by their granular texture.
Slate:
Slate is a metamorphosed mudstone with a fine grained texture. Due to the alignment of the minerals that make up the rock, slate has a characteristics cleavage plane which enables the rock to be split into very thin sheets.
Limestone:
Limestone is a sedimentary rock composed mainly of the mineral calcite (CaCO3). Most limestones were deposited beneath the sea as a result of the accumilation of fossil shell debris or as a consiquence of the precipitation of calcite in calcium rich waters. Limestones can vary tremendously in appearance, colour and texture and is one of the most abundant naturally occurring natural stones.
Travertine:
Travertine is technically a limestone and is formed by the gradual deposition of calcium and magnesium salts, usually in hot springs or other situations where saturated solutions naturally occur. It is characterised by the presence of voids within the matrix which can vary hugely, both in the quantity in which they occur and in the form that they take.
Marble:
Marble is a metamorphosed limestone and principally composed of recrystalised calcite. Pure marble is white but the prescence of minerals other than calcite leads to the variation in colour and patterning.
Granite:
In the natural stone trade, granite is used to describe a wide range of hard and durable rocks with a crystalline appearance made up of different coloured minerals. To the geologist, granites are are coarse-grained, plutonic igneous rocks composed of feldspar, quartz and mica.
Basalt:
A dark-coloured, fine grained basic igneous volcanic rock which has a dense fine grained texture.
Quartzite:
Quartzites are metamorphosed sandstones which have been subjected to extreme conditions of temperature and pressure. The end result is a dense and durable stone with a light colour and sugary appearance and texture.