Materials are subdivided into these four macro categories:
– GRANITE – MARBLE – ONYX – NATURAL STONES
(sandstone and limestone)
Granite is born out of the fire. This is a fiery igneous rock, also called magmatic, generated by the cooling and crystallization of a molten magma.
The magma that comes to the surface, undergoes a sudden change of temperature and gives rise to effusive rocks, when, instead, it solidifies slowly below Earth’s surface it becomes intrusive rock.
Intrusive rocks cool down slowly and this allows the gradual formation of well visible crystals, often also of large granules. In this case we talk about granitoid rocks, which are collected in deep large accumulations of the so-called batoliti. Intrusive rocks can be led to the surface due to weather conditions that erode the cover or thanks to movements of the earth’s crust.
Granites are the most representative intrusive rocks: they consist mainly of minerals such as quartz, orthoclase (potassium feldspar), mica, which also determine the particular coloration.
Porphyrous granites, for example, are characterized by large orthoclase crystals (white or grayish).
Hardness is therefore the main characteristic of granite and is highlighted in its ability not to be affected by acidic agents (fruit, vegetables, cleaning products), which results in great value in the use in delicate areas such as kitchen. The natural presence of micropores (which we find in all natural stones) characterize a predisposition to absorb any liquid substances that may generate more or less darker spots depending on the type of liquid absorbed.
This problem is solved by stain treatment, a kind of processing to which granite is subjected to limit the absorption of the liquids and make it immune to haloes.
The presence of quartz and minerals, in different proportions, configures its chromatic aspect and, in a significant way, the different spotted or veined geometry. Granite is suitable for different types of workmanship, but the most suitable finishing for internal furnishing is certainly the polishing: this is obtained by smoothing the granite surface with increasing grain abrasives to obtain a mirror effect; then it is further processed with a layer of wax to increase its shine and protection.
Granite, as compared to other harder stones, keeps the finish much longer due to its hardness caused by the content of quartz and silicon.
Usually in housing construction is used to coat stairs or thresholds.
Marble is “alive” and is born from a process called metamorphism (change inform). Marble is a rock originated from limestones that are transformed due to several factors, in particular, temperature and pressure are responsible, increasing with the depth (on average 10 to 30 ° C per kilometer, the so called geothermal gradient). Marbles are generated by thermal or contact metamorphism, due to a significant temperature increases (for example due to direct contact with magma), that trigger the transformation of limestones into saccharoidal marbles, or consisting of large crystals.
Under our feet, therefore, there is a continuous work and the metamorphic rocks we can see on the surface, rose only due to the activity of atmospheric agents or movements of the earth’s crust.
Marble has a millennial history, dating back to the age of copper:
in ancient Greece the marble was used in architecture and sculpture;
In ancient Rome marble was a fundamental element of public and private architecture: it was used for coating and adornment of buildings, sculpture and furnishings (such as travertine).
After a period of decline, following the fall of Roman West Empire, marble returned to its original splendor after the year 1000, used for the construction of churches and sacred works (see the famous statuary white of Carrara and the various italian Breccie);
From the Renaissance onwards the marble has not ceased to be a fundamental element in sculpture and architecture, up to today.
But the spread of marble is not just about the history of art. Its resistance and waterproof properties make it suitable for everyday use: floors, staircases, tiles, window sills, worktops, ornamental sinks and even modern objects.
Marbles can have different types of grain and contain up to 99% of calcite. Often grains indicate the impurities of the composition while color is determined by the presence of subsidiary minerals.
Apuani marbles, whitewashed, are pure, ie almost entirely made of calcite and this is the main cause of the white color that characterizes them. The deep valleys and the arid walls of the Apuane Alps have formed due to a sedimentation (especially of limestones) that took place in the marine environment millions of years ago. Pressures exerted by other marine deposits have caused, due to rising temperatures, the metamorphic phenomena that generated the precious Carrara white marbles, whose original rock was a limestone very similar to that which forms the coral reefs of the tropical seas and dates back to the Giurassico Inferiore geological period, about 190 million years ago. Then, in later periods, it has undergone transformations that have modified the crystalline structure into microscopic calcium carbonate crystals.
Marble varieties differ according to the quarries from which they are extracted.
Here are some of the main features of the most famous Italian marbles in the world, namely those from the Apuan Alps:
White Carrara – its peculiarity is to contain very limited quantities of impurities. The plates have a white-pearl background paste where occasionally small gray grains may also be present.
Statuary – surely among the most valuable. It has been used for sculptures, since Roman times, for its white-ivory coloring.
Venatino – whose main feature is to present fine veins, but many gray that cross a white or slightly greyish background composition.
Arabescato – very similar to Venato as a color but unlike the latter, it has veins that draw on the base a plot similar to an arabesque.
Calacatta – has a yellow cream veins on a white or ivory background paste. It is a marble of great value and its availability is rather limited.
Bardiglio – whose base paste assumes a gray color due to the widespread presence of fine crystals of pyrite.
Cipollino – which has very marked streaks of gray-greenish color that recall the inner structure of the onion.
Some compact limestones are precious and very used in the building as marble substitutes. However, these are sedimentary rocks that derive from the action of living organisms; In fact, they often include fossils (such as the Pearled of Sicily) and are composed of calcite, dolomite and aragonite.
Among the best known varieties are Botticino di Brescia (beige); Red Orobico Arabescato; the Serena stone; the stone of Trani and the Bronzetto, the classic Roman travertine, the Portoro of Piedmont (dark colored with lighter gold colored veins).
We have also a special case, that of the alabaster: it is a kind of microcrystalline chalk type (also a sedimentary rock), whose coloration is due to the presence of various types of minerals. Volterra’s alabaster is a very valuable rock that is used mainly for ornamental objects. The skill of craftsmen combined with the rock properties can give the artifacts inimitable the play of light and transparency.
The noble and prestigious Italian marble is used for the lining and decoration of interior and exterior spaces, as well as the creation of real works of art such as sculptures. The most popular marble type is the Bianco di Carrara, extracted from ancient times and has always been recognized as a symbol of style, quality and durability. We offer, in addition to this marble, a wide range of natural stones for the most demanding customers.
The advantages of Italian marbles are:
– High degree of machinability
– Very high polishability
– Cold resistance
– Easy to maintain
– Originality and style
Natural stone is a stone of sandstone origin; it is therefore a sedimentary rock composed of granules that have the size of the sand. It is therefore the union of granules of different origin that settle down together with wind or water, often after a long journey. The composition of the stone therefore depends on the resistance to abrasion and the chemical alteration of the different granules. Usually, natural stone has a large amount of quartz, mineral which, thanks to its strength, is one of the most common constituents of these rocks. The granules are bound together by a cement originating from the chemical precipitation of minerals formed by ions present in the circulating water between the interstitial pores, commonly calcium carbonate is found as cement, in both calcite and aragonite form, less abundantly silica or sometimes an iron oxide.
Being easy to work and good looking, natural stone is widely used in construction.
Compact stone from discrete properties and a uniform blue-gray color, also called “sky-color”, which distinguishes it. Extremely easy to work, it is used for sculptural works and urban furnishings, in the field of restoration and in prestige relizations, environments of representation, business, banks and offices.
Serena stone is best suited for indoor use, Extraforte stone for ornamental use and for outdoor use, Pietro Colombino is a calcarenite and its superior properties make it suitable for outdoor flooring.
Exterior flooring and outdoor stone coatings are the first things we look at in a home.
Natural stone is a product that makes a difference in the exterior presentation of our house, anyway the eye wants its part, with a natural product we can have a great aesthetic performance and unparalleled durability.
ONYX (OR ALABASTER)
Onyx in mineralogy are igneous rocks, crypto-crystalline forms of quartz (SiO2) agate subtype (7 mohs hardness) from which they differ for being streaked.
Commercially the term expanded to include the most aesthetic alabaster, say geologists. But the first text written to create terminological confusion with modern geology is the Genesis where it is referred to as ‘onyx stone’, the Greeks used the term “onux”, which means nails, and even the ancient Romans called “Lapis Onyx” the precious Alabastri of the Nile Valley originally mined in the Egyptian city of Alabastron, from which comes the Greek term Alabastros according to Pliny.
Just Pliny the old – born in Como among other things – in the book XXXVI of his Historia Naturalis in which he speaks of marbles and stones, reports that already at his times someone called them alabaster instead of onyx, and that were the best type of containers in preserving ointments over time.
Marble cutters in Egyptian and Greek tradition have continued to call them onyxes while for geologists they are alabaster (also called stalactites). Anyway case, they are sedimentary rocks (2-3 mohs hardness) similar to the travertines that originate from calcium carbonate precipitation in very quiet underground caves (grottoes) and have zoned structure composed of large crystals of calcite.
They have always been associated with luxury and decorations for their transparent and multicolored appearance; in ancient times the Egyptian alabasters were famous and in the late Roman-medieval times the Tuscan ones (but also found on the Carso and in Lombardy).
They are intensively used as semi-precious in costume jewelry for necklaces or pendants, in furnishings and interior coating, backlit by normal lights give a unique aesthetic effect, for example in the windows of the mausoleum of Galla Placidia (III century, Ravenna) they are used Instead of the glasses.
These are delicate rocks and discolor if exposed for a few years in direct sunlight, which is why they are not usually used outside, with adequate protective treatment can be used as indoor flooring
In commercial language they are often assimilated to the marbles with which they share composition (both have prevalent calcium carbonate content).
calcite, calcium sulphate
Holocene 10,000 years ago
Onyx colors are: White – Fantastic – Yellow – Multicolor – Gold
– Pink – Red – Emerald – Green Onice
There are several ways to work the surface of marbles and stones
This work with the use of automatic machines, involves polishing the floor, passing from very large abrasive grains to fine grains.
This workmanship is very suitable for indoor use, as in the outside along years the polishing tends to disappear because of acid rain that characterizes our times.
Smoothing (or egg-skin)
Marble sanding is very suitable for outdoor and indoor use.
It gives the marble a very satin look in with no mirroring and where no reflections can be seen.
Outdoors is a very long lasting process, since acid rain does not evidently damage it.
Brushing of marble consists of an aging process made with a grinder made with an abrasive plastic material.
Such marble processing generates a so-called orange peel surface, which gives the marble an ancient appearance and time worked.
It is very suitable for both interior and exterior workmanship.
Brushed marble for outdoor fits very well with another outdoor workmanship, “The Bocciardatura”
This machining can be carried out with machines either at the fabric and on the yard, by polishers who can work immediately after the laying of the marble.
Bocciardatura (or hammering)
Marble hammering is carried out at the stonemason with special machines that by means of plates turning on themselves on the surface of the marble beat the marble surface, with some spikes generating small grooves and a hammered surface.
This work can only be done on some types of marble, since not all marbles bear the impact with this workmanship.
It is a workmanship designated for exterior and for some slightly pspecial interior walls.
It grants marble or granite when used in outdoor anti-slip characteristics
The flaming of the marble is carried out with very high temperature oxidic tubes. It can be done on some types of marble and practically on all granites.
It gives to the treated piece of marble a natural break look that can in turn be brushed, creating a flamed-brushed surface very beautiful to see.
The flamed marble or granite is very well indicated for both facade cladding and outdoor pavements as it is in its nature non-slip.
It is a beautiful marble workmanship that the builder needs to keep in mind to beautify his houses.
Marble rolling is done by marble workers, through a machine that is made up of a toothed roller that rotates at high speed on the marble surface.
This machine carves on the marble rows that can be more or less marked and more or less deep depending on the roll used to perform the work.
It is a workmanship indicated for both interior walls and external floors as non-slipping
Acid etching is carried out by the marble worker by immersing the marble in special acid tanks.
Marble before etching can be “bocciardato” or sandblasted to increase the wear effect by acidification.
The effect you get is very similar to brushing, but gives the marble a much older look.
It’s a workmanship that can not be done at the yard, but it can only be done at the factory.
Marble sandblasting is performed by the marble worker and involves a very marked satin finish of the marble.
In addition to this workmanship, marble can be acidified or patinated after working.
By the nature of the work, it gives the marble an ideal non-slip surface for outdoor use.
Not all marbles can be sandblasted, generally too soft marble are excluded or those with excessive holes.
The tumbling of the marble is carried out by the marble workers by means of large “buratti”(some sort of tumbler) which give the marble a very “worn out” appearance.
The sizes of tumbled marble tiles rarely exceed the size of 30 x 30 x 2.
Occasionally larger sizes can be produced but production costs are high.
Most used tumbled tiles are 10 x 10 x 1 in size: the so-called Palladian.
If you want it after tumbling, marble can be treated with special paints that give the so treated marble a shiny look.
Marble chiseling can be done either by hand or by machine.
Usually today we use the machines that give the marble so treated a very rustic appearance.
It is used extensively for the execution of window sills.
Nowadays also robots can print, very characteristic, beautiful designs on the marble slabs.