Granite (it.granito< lot.granum- corn) is crystal grey or pink grey rock, which is used for decoration, construction and sculptures.
Granite and minerals that make up this rock. Usually several kinds of minerals are found in rock. Their size and structure depends on rock origin Three main minerals constituting granite which is hard-grain magmatic rock, can be seen with the naked eye: quartz (grey minerals), feldspar (orthoclase) (pink and white minerals) and mica (black).
Granite of magmatic origin, e.g.
The formation of granite.
Geological processes occur in permanent cycles. During these cycles, chemical compositions, minerals and rocks are reallocated in the depths of earth and its surface. The driving force of internal earth processes such as metamorphism and orogeny is the heat of the earth's depths. The processes of the surface such as decay are stimulated by the sun energy. The deeper rock is in the earth, the more pressed it is by the rock above it and the higher temperature it is. Due to the pressure and heat, rocks change or metamorphose because minerals recrystalize. The changed rocks are called metamorphic rocks (i.e. gneiss, marble, schist and migmatite).
'Bararp' (gneiss) Western Sweden, e.g.
Under the high temperature and high pressure magmatic or aqueous rocks can metamorphose and turn to gneiss. Gneiss consists of harder grains than crystal schist does and it is easily recognized since its minerals are located in strips. These layers can be unequal where the rock is rucked due to the pressure. This variety of rock is used in construction works, for the decoration and manufacture of tombstone monuments in Lithuania. It is imported to Lithuania from Sweden, Finland, Africa, India, Russia, Ukraine etc.
This rock is sparser than the rocks of magmatic origin. Its density is 2,5 to 2,7 tons per cubic metre.
The density of the rock is directly proportional to the durability of its polished surface.
Processing: bushhammering, burning (unadvisable), abrasion, polish.
The beauty of the naturally formed minerals' patterns, which open up after polishing, particularly characterizes this type of rock.
When the chalk-stone (chalk) is under the very high temperature, new calcite crystals grows and forms solid rock known as marble. Sometimes marble is mixed with very similar rock called quartzite. However, marble is softer and it can be easily scratched with the knife. The marble of average grain is similar to sugar and, therefore, is called 'sugar'.
"Calacatta Parrara" marble, Italy, e.g.
The most famous marble is taken from Carrara quarry in Toscana (Italy). Michelangelo used it as a local rock for his sculptures.
Currently, marble is used in Lithuania for home interior decoration (fireplaces, windowsills, floor, tables etc.). Due to the softness (approx. 2,5 tons per cubic metre), marble is not recommended for house exterior decoration and other products. Lithuanian climate zone is characterized by the frequent acid rains, which erode porous mineral structure of marble. Marble also has a negative characteristic to 'absorb' all the impurities which appears on its surface. Due to the porosity of marble, it is often impossible to clean 'soaked' marks.
When the rocks of the earth crust and mantle melt, they form magma, which is able to erupt through the volcanoes in the surface of earth. This is a process of effusive magmatic (effusion (lot. effusio - overflow, outflow) in geology is the overflow of fluid lava from volcano to the earth surface) rocks formation. Archetypal example is basalt. Effusive rocks formed in all the continents of the earth.
Basalt rocks, Northern Ireland
This rock is mainly used as a strong building material (for bearing walls, stairs, roadways). It is very suitable both for inside and outside works.
It is most often processed by rifting, cutting and abrading. Polish is unadvisable since the polished surface of the rock is nondurable due to the porosity and insufficient density. The rock is imported into Lithuania from China and is used in construction works.
The rocks that form in the depths of earth while the fluid magma freezes are called intrusive magmatic (intrusion (lot. intrusus - hustled into) in geology is a body which is formed in the depths of earth crust from the thrown in and crystallized magma) rocks. They are also referred as plutonic rocks according to Pluto, which is the name of Greek Underworld God. One of such rocks is granite, which sometimes forms huge solids in the mountain zones.
Granite is very widely spread intrusive rock, which is mainly made of hard grains of quartz, feldspar and mica. Separate grains are big since they have been formed while the magma slowly gets cool in the depths of the earth. The color of granite samples which are usually patchy, ranges from grey to red, depending on the ratio of its constituting minerals. Granite is found in many countries of the world. There are many varieties of granite, e.g. gabbro, diorite, norite, anortosite, labradorite etc. The rocks are divided according to the ratio of minerals in their composition.
Gabbro rock consists of the following minerals: pyroxene, plagioclase and olivine. Pyroxene provides gabbro rock dark grey or black color, which shows up after the polish of granite.
"Black EGC" granite, Sweden e.g.
Gabbro granite is imported into Lithuania from Finland, Sweden and Russia. Since the granite is expensive it is often used for the interior decoration of luxury buildings or manufacture of tombstone monuments. The density of this granite (2,9 - 3,3 tons per cubic metre) and slender porosity determine easy polish and durability of polished surface.
Processing: bushhammering, burning, abrasion, tooling, split and polish. This granite is characterized by evident contrast between colors of bushhammered and polished surfaces, i.e. polished surface is black and bushhammered or abraded surface is bright grey. Sculptors and stonecutters ably use the feature of granite while creating and manufacturing various tombstone monuments and sculptures.
||‚Uolienos ir mineralai' (‚Rocks and minerals') leidykla "Alma litera" Vilnius, 1996.|
'Tarptautiniø þodþiø þodynas' (,Dictionary of international words') Publishing House UAB "Gimtinë" 1999.
Website of joint-stock company 'Emmaboda Granit '
Website : www.krugosvet.ru
It was written by
The director of UAB 'Olivino Gabras'