White, Black, Yellow and varicoloured carbonatic rocks,
produced by recrystallization of Limestones with enough to take a
polish. Most of these materials originating from regional metamorphism
of High pressure and low-medium temperature. Marbles may be variously
coloured or banded, depending on their chemical and mineralogical
composition (mostly Calcite and Dolomite, Tremolite and others elements
in traces).
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In these commercial term are represented all the materials
of typical silicatic composition. Granites and Granodiorites especially
include intrusive magmatic rocks with medium-coarse grain, various
colours and a consistence of Quartz, Alkali-feldspar, Biotite and
Muscovite. Granites can be formed by partial melting or granitization
of old continental crust ( Gneiss, Migmatites ) or by fractional crystallization
of basaltic magma (Gabbros, Anorthosites). |
| These term are used for indicate all the sedimentary
rocks composed mainly of Calcite and Dolomite, which is often of organic,
chemical and detrital origin. These rocks are not recrystallizated
by the metamorphism, and can be divided into layered limestones and
massive limestones. |
These types of sedimentary and metamorphic rocks are
represented by : Quartzites and Sandstones (silicatic rocks) , Shales
and Slates (formed by orientation of schistose pelitic rocks) and
Serpentinites. The best interest are for the utilisation with natural
splitting in slabs. |
