The popular stone types that are used today are identified through four categories:
SEDIMENTARY STONE: came from organic elements such as glaciers, rivers, wind, oceans, and plants. Tiny sedimentary pieces broke off from these elements and accumulated to form rock beds. They are made by millions of years of heat and pressure.
(1) LIMESTONE:Mainly consists of calcite. It does not show much graining or crystalline structure. It has a smooth granular surface. Varies in hardness. Some dense limestone are polished. Common colors are black, grey, white, yellow or brown. It is more likely to stain than marble. Limestone has been known to contain lime from seawater.
(2) SANDSTONE:Is a very durable formation of quartz grains (sand). Usually formed in light brown or red colors. Categorized by the most popular sandstone bonding agents such as silica, calcium, clay, and iron oxide.
(3) SOAPSTONE:A very soft stone made of a variety of talc. A dense mineral wears well and is often resistant to stains.
(4) FOSSILSTONE:Considered a limestone that contains natural fossils such as sea shells and plants.
(5) TRAVERTINE: It is formed through the accumulation of calcite from hot springs. It contains many holes that come from water flowing through the stone. These holes are filled with synthetic resins or cements. Requires lots of maintenance if the holes are not filled. Classified as a limestone and a marble.
METAMORPHIC STONE originates from a natural change from one type of stone to another type through the mixture of heat, pressure, and minerals. The change may be a development of a crystalline formation, a texture change, or a color change.
(1) MARBLE: A recrystallized limestone that formed when the limestone softened from heat and pressure and recrystallized into marble where mineral changes occurred. The main consistency is calcium and dolomite. Ranges in many colors, usually heavily veined, and shows many grains. Hardness rates from 2.5 to five on the MOH Scale.
(2) SLATE:A fine-grained metamorphic stone that formed from clay, sedimentary rock shale, and sometimes quartz. Very thin and can break easily. Usually black, grey, or green.
(3) SERPENTINE:Identified by its marks, which look like the skin of a serpent. Most popular colors are green and brown. Hardness rates from 2.5 to four on the MOH Scale. Contains serpentine minerals has lots of magnesium, and has an igneous origin. Does not always react well to recrystallization or diamond polishing.
IGNEOUS STONE are mainly formed through volcanic material such as magma. Underneath the Earth’s surface, liquid magma cooled and solidified. Mineral gases and liquids penetrated into the stone and created new crystalline formations with various colors.
(1) GRANITE:Primarily made of Quartz (35%), Feldspar (45%) and Potassium. Usually has darker colors. Contains very little calcite, if any. Provides a heavy crystalline and granular appearance with mineral grains. It is very hard material and easier to maintain than marble. Yet, it is still porous and will stain. There are different types of granite depending on the percentage mix of quartz, mica and feldspar. Black granite known as an Anorthosite. It contains very little quartz and feldspar and has a different composition than true granite.
MAN-MADE STONEs are derived of unnatural mixtures such resin or cement with the additive of stone chips.
(1) TERRAZZO:Marble and granite chips embedded in a cement composition.
(2) AGGLOMERATE or CONGLOMERATE:Marble chips embedded in a colored resin composition.
(3) CULTURED or FAUX MARBLE:A mix of resins that are painted or mixed with a paint to look like marble.