What Is Natural Stone?

Natural stones are stones produced by the Earth. Quarried stone is processed by polishing, brushing and hammering to improve its features, such as shine and smoothness. The most commonly used natural stones are granite, marble, limestones and sandstone.

Granite

• Granite stones form from magma, commonly known as lava. Common ingredients include feldspar and quartz (feldspar imparts its red color). Granite also contains mica and other minerals in smaller amounts, including apatite, zircon, magnetite, sphene and ilmenite, which gives it its characteristic shade and crystalline structure. They are stronger than many other natural stones and tolerate weathering as well. They are mainly used as building material.

Marble

• Marble is formed after recrystallization of limestones. The marble stone has variable strengths, so they are classified by the soundness of stones into four groups:
  The first group consists of marble that doesn't have any structural defects; the second group of marble is only slightly physically flawed; the third group includes marbles that have fissures, voids and flaws; and the fourth group of marbles have large flaws, but they have increased decorative values because of their high colors.

Limestones

• Limestones are composed of calcium carbonate or lime, but can also contain magnesium carbonate in small amounts. Depending on their recrystallization, limestones could look different from one another, thus they have different commercial values. They might have different natural characteristics such as streaks or spots, fossils or shell formations, honeycomb formations, reedy formations, pit holes and open texture streaks.

Sandstone

• Sandstones are formed from loose grains or rock. They are used extensively in construction of building and pavements because they are resistant to weathering. They contain quartz, and other minerals such as feldspar and mica. Sandstones are also used for manufacturing of cement.

Quartzite

• Quartzite is made after metamorphosing of sandstones, including silica, quartz and mica. Quartzite might contain other minerals such as feldspar and zircon.

Slates

• Slates are a type of stone that forms over long periods from clay metamorphosing into stones. They can be split into thin sheets. Commercially, they are used on interiors and exteriors.