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Granite consists mainly of quartz, with a granular structure and crystals, different in size and color. Granite has high stability to friction. Due to the excellent chemical, physical and mechanical properties, granite got a wide use in building for the external finishing. In addition, table-tops for a kitchen, stairs and fountains are made from granite.
Granite is a magmatic breed, containing 60-65% feldspar (orthoclase and plagioclase), 20-30% quartz and 5-10% biotite, muscovite, sometimes augite. The most widespread structure of granite is even-grained type. Texture is massive. The basic colour background of granite is conditioned by coloring of prevailing feldspar - pink, yellow, red, green, grey and other. High decorative and durability qualities of granite and considerable prevalence of granite deposits, determine his wide use in the different types of building and in monumental architecture.
The main advantage of granite is its natural hardness. Excellent material for the outward finishing of facades, stages and chaffs. A wide colour gamut opens designers unlimited possibilities. Most breeds have low weariness and water absorption.
Breed, formed from orthosite (white or pink), quartz and mica (biotite and muscovite), sometimes with other additional minerals. The hardness of granite is due to the presence of quartz, which can exceed 70%. According to varieties, it presents a particle more or less shallow and color from white to grey, pink and red, with the characteristically glimmered disseminations. In the modern terms of processing granite is cut and polished by a diamond. In addition, it is possible to reach its mirror polish. This is the stone, used in building, which more than others resists inclement weathers, possesses ever-high resistance to compression (from 800 to 2.200 kg/sq.m.). It is used for revetment of columns, balconies, stairs, monuments, to furniture etc.
- In ordinary speech, in the technical and commercial meanings, this name determines magmatic breeds - both intrusive and effusive granit breeds possesses hardness and workability, comparable with a granite. In most cases their resistance to squashing and pressure is similarly very high. Gneises, formed by the breeds of volcanic origin, which possess identical or a bit different from granite mineralogical structure, are defined as granite breeds. In other words, granite breeds, in-use as build materials, include, except for scientifically certain granites, syenite, diorite, gabbro, porphyry, liparite, trachyte, andesite, basalt, diabase, feldspatoid, gneis, sericio, slate quartzite, worm-pipe, a granodiorite and other varieties and subspecieses of the higher mentioned structures.
Many of the enumerated breeds, from trachyte and further, possess the commercial names, certain their use or producer. Nobody would sell as granite neither a trachyte neither gneis neither sericio, neither slate quartzite nor worm-pipe, as well as of their characteristic original appearance which is frequently impossible to mix with anything else.
The word “granite” determines here only descriptions of hardness and workability, very different from similar descriptions of marble. A vagueness and ambiguity can arise between the commercial, technical and scientific names, vice versa, between granites, syenites, diorites, porphyries because of their appearance which can be very similar for not-specialist and easily results in deception, both because of the old names and the great number of stratifications in the different types of breed of the same family, or because of other reasons.
So ancient syenite of Egypt, of a red-pink color, from which obelisks are made, was brought to Rome in an imperial epoch, and was obtained in Siene (today Assouan), actually is an amfobolitic granite.
And black granite of Angola, which is obtained in the valley of Val di Ossola, not far from the township of Premosello, actually is an amfobolitic gabbro. Adamello or Tonalite (obtained in Passo del Tonale) granite - there is quartz biotito-amfibolitic chlorite with many varieties.
As it was stated, these variations or errors in the names changed nothing - neither from a technical viewpoint nor from the viewpoint of practical application. In any case the question is about granite materials with all qualities of longevity, inherent materials, defined from the scientific point of view as granites.
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