An Introduction to Stone
Natural stone products are powerful enhancements to any building project, and high end results are achieved and associated with the warmth of a natural product. Below is a brief description in geological and commercial terms, of the classifications and conceptual definitions of the stones that are commonly used for ornamental and for construction purposes. Please reach out to us with any stone questions and the best stone for your application.
Commercial Definitions – Rock Classification terms used in the stone industry
To fully appreciate the beauty and unique qualities of any ornamental stone, you must see and feel it for yourself! Please call us to set up an appointment. We will be happy to assist you in this experience.
Granite
The name granite derives from the Latin (“granum” = grain) and refers to the granular texture of the stone itself. The general impression of granite is always of a light-colored rock, regardless of whether it looks gray, yellowish, brownish, bluish or reddish. Granite is a widely used stone for building and decorative work. It wears extremely well, is highly resistant to weathering and is the most durable architectural building stone.
The increasing popularity of granite is a result of its beauty and versatility. Used in a wide range of commercial and residential applications, granite is ideal for tile floors, walls, and countertops, as well as exterior applications such as pavers and wall cladding.
Granite is ideal for kitchen counter tops, islands, bar tops, fireplace surrounds, and dining tables because it is not only functional and durable, but highly attractive.
More granite quarries are discovered each year increasing the color choices and keeping prices competitive. Granite is quarried worldwide.
Marble
The term, marble (Greek, “shimmering block of stone”), is defined in different ways. In scientific petrography, it is defined as a calcitic metamorphic rock, the true crystalline marble. In the building industry, any solid limestone which will take a polish is called marble.Marble has a unique characteristic in that no two pieces are alike and differs from limestone in the following ways:
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Crystalline Marble
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Limestone
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Coarse-grained
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Fine-grained
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Crystals visible with the naked eye
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Crystals indiscernible with the naked eye
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Sparry fracture
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Fine-grained, dull fracture
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Translucent at edges
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Opaque at edges
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No cavities
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Occasional cavities
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No fossils
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Frequent fossils
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Marble is a very elegant and luxurious stone. Its beauty, originality and versatility will allow it to be used in many applications such as floor tiles, wall tiles, fireplaces, columns, water tables, steps, thresholds, and windowsills, etc. For kitchen surfaces, it is best to use a honed marble for ease of maintenance.
Throughout the house, marble will shine best in the bath, but can be used for every surface including vanity countertops, shower walls, tub decks, flooring – wherever your imagination allows!
Limestone
Limestone is a sandy sedimentary rock formed close to the earth’s surface and often captures fossilized plant and animal remains. Like marble and granite, limestone is processed for a wide range of interior and exterior building applications including floor tiles, wall tiles, fireplaces, columns, water tables, steps, thresholds and windowsills, etc.Limestone can be polished to a gloss finish, but it is more commonly known for its honed (matte), tumbled (antique or acid-washed), and natural (rough) finishes.
Colors are, typically, more neutral tones.In the building industry, any solid limestone which will take a polish is called a marble. Therefore, stones such as popular Crema Marfil are often called marble, but are scientifically a limestone that has been polished to a high gloss.
Travertine
Travertine is a dense, compacted form of limestone deposited by mineral springs, especially hot springs. Travertine often has a fibrous or concentric appearance and exists in white, tan and cream-colored varieties.
Known for its porosity, travertine is composed primarily of calcium carbonate. Slabs and tiles are cut from blocks with the veining (regular cut) or across the veining (cross cut). Processors of this material will market the stones as is, with the holes for a more rustic, antique look; or; without the cavities by filling them with a tinted epoxy and then hone or polish the surface to achieve a solid effect. Some travertine takes a polish similar to marble.
Travertine is frequently used as a building material and is the classic construction material for facing and paving. It is used widely for interior and exterior applications including floor tiles, wall tiles, fireplaces, columns, steps, and counter surfaces for kitchens, bars, or baths.
Sandstone
Sandstone is a sedimentary rock that is composed mainly of sand-sized minerals or rock grains of quartz or feldspar cemented together by silica and calcium carbonate. These particles are usually from pre-existing rocks – igneous, metamorphic, and other sedimentary rocks. They are generally found under seabed, riverbed, or desert areas. Particles start depositing one above another in layers, influenced by some type of current (wind, waves, flowing water, or glacier).
Like sand, sandstone may be any color, but usually tan or yellow (a blend of the clear quartz with the dark amber feldspar), terracotta ranging from pink to dark red (due to iron oxide content), or purple-hued (manganese added). Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions.
Some sandstone is both resistant to weathering and easy to work. This makes sandstone a common building and paving material. The natural beauty of sandstone makes it suitable for interior as well as exterior decoration such as: wall cladding, flooring, countertops, and sculpture.
Quartzite
Quartzite is composed of sandstone that has been metamorphosed, changed under extreme heat and pressure over time, resulting in its strong, granite-like properties. Quartzite is much more durable than the parent rock.
Pure quartzite is usually white to gray, though depending on iron oxide or mineral impurities present, can be various shades of pink, red, yellow, orange and blue.
Quartzite is a decorative stone and may be used for walls, roofing tiles, countertops, flooring and stair steps.
Slate
Slate is a fine-grained metamorphic rock that splits into thin and smooth-surfaced layers. It is an economical and decorative choice used in a wide range of interior and exterior applications.The most common building application for slate is flooring, wall tiles, roof tiles, and fireplace surrounds. Slate is also widely used in beautiful landscape design for patios and pathways.
Soapstone
Soapstone is a metamorphic rock basically composed of the mineral, talc. This natural quarried stone is softer than most other natural stones. Although a soft stone, soapstone is a very dense (non-porous) stone.
It is wrong to associate softness with porosity; soapstone is denser than marble, slate, limestone and even granite. Because soapstone is so dense, it will not stain if anything is spilled on the surface since it will not penetrate the stone. Other natural stones, including granite, may stain if not properly sealed.
Very easy to maintain, soapstone can be cleaned with any common household cleaners. The only maintenance required for soapstone, is the occasional application of mineral oil.
Onyx
Onyx is a semi-precious stone, mineral in formation, not a rock. It is a carbonate (Calcite) formed by quartz crystals, fused together by nature into translucent layers of stone, revealing a rainbow of colors ranging from creamy white, gold and amber to orange, red, brown, deep green and gray.
A natural process of heat and pressure creates a crystalline stone rich in color, pattern, warmth, and opalescence.Its beauty and translucency allow Onyx to be used in a variety of applications ranging from flooring, walls, fireplace surrounds and mantels, countertops, bathtubs, pedestal sinks, dining tables, cocktail tables, extension tables, consoles and chairs.
Geologically Discussing Stone
Natural stone is a powerful enhancement to any building project and the high end results achieved are associated with the stone’s intrinsic warmth and beauty. It is important to know something about the origin of stone – how it was created and what properties make it best suited for your designs. We will begin with a little science.
Petrography – the study of rocks and minerals.
Minerals – can be considered naturally occurring organic compounds with a structure and composition confined within fixed parameters and consistently exhibiting a characteristic range of physical properties.
Rocks – can be defined as extensive solid stony bodies usually composed of a small assortment of minerals present in varying proportions, constituting a significant part of the earth’s crust. Rocks are divided into three major groups and, then, subdivided into several categories.
3 Main Types of Stone: Igneous, Sedimentary, and Metamorphic
Igneous – A rock formed by molten magma or lava cooling and becoming solid, with or without crystallization. From the Latin, ignis, meaning “born of fire”.Igneous processes began some 4.6 billion years ago with most igneous rocks being from the Pre-Cambrian period. There are over 700 types of igneous rocks with diverse properties, most having formed beneath the earth’s crust.
Igneous Extrusive – Volcanic fine-grained, dark-colored igneous rock formed by the crystallization of lava on the earth’s surface as magma (lava) cooled quickly.
Basalt – originated by most recent volcanoes that produced flows of black lava that spread out on the earth’s surface and hardened into a black and gray stone. Presently, the commercial value of this stone is growing rapidly.
Igneous Intrusive – Plutonic coarse-grained rock composed primarily of quartz, feldspar, mica, and various minerals formed under extremely high temperature and pressure below the earth’s crust.
Named after Pluto, Roman God of the Underworld, plutonic rocks are usually found within mountain ranges.
Granite
Sedimentary – rock formed, mainly, from the weathered remains of other rocks and by the deposits of marine life which solidify in layers under pressure.Sediment is deposited out of air, ice, or water flows which carry the suspended particles. It is banded, stratified, and often presents presence of fossils.The main ingredient in sedimentary rock is Silica (quartz), in other words sand. These are the only rocks that contain fossils since the shape of the particles allow micro-organisms to colonize there.
| Dolomite | Limestone | Sandstone | Travertine |
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| A rare rock, formed by the precipitation of seawater, lagoons and lakes in continental areas. | A rock composed primarily of calcium carbonate and sediment. Ocean water or secretions of algae and coral are the basis for limestone. | A very common rock, formed primarily by sand deposited where there was once a beach. Since the sand had been wet at one time, it is thoroughly stratified and easily quarried. | Rock formed by the evaporation of spring water, rich in calcium and carbonate, both in rivers near waterfalls and in caves by deposits of thermal water in subterranean cavities. Travertine is often beautifully colored and banded due to the presence of iron compounds and other impurities. It is a dense, compacted form of limestone. |
Metamorphic – a pre-existing rock that is changed, or transformed, under heat or pressure (or both) causing a chemical or physical change to the rock.Any of the rock types – igneous, sedimentary, or metamorphic – can be altered in appearance, density, and crystalline structure by high temperature or intense pressure and are classified according to texture or the combination of minerals present.
Slate – a very fine-grained metamorphic rock derived from the sedimentary rock shale. Characterized by an excellent parallel cleavage entirely independent of the original bedding, by which cleavage the slate may be split easily into relatively thin slabs.
Marble – a crystalline rock composed predominantly of crystalline grains of calcite, dolomite or serpentine, and capable of taking a polish. Marble is a metamorphic rock that once was a limestone, but over time the combination of intense heat and pressure cased the limestone to crystallize again. Different substances entered the composition of the stone during this process, creating the infinite variation of colors and veining.
Quartzite – is a rock composed of sandstone that has been metamorphosed. Quartzite is much harder, yet looks similar to the parent rock, sandstone. It forms from sandstone that has come into contact with deeply buried magmas. The best way to tell quartzite from sandstone is to break the rocks. Sandstone will shatter into many individual grains of sand while quartzite will break across the grain.