I have always known that granite was a very versatile material.
But only recently while looking around on the internet, did I find
out, just how versatile granite really is. We are primarily interested
in it's uses as a gem or decorative material. But I now see it has
One decorative granite item we have seen a lot of, is the granite
sphere. Granite spheres come in many great colors. There is a very
nice granite from Llano, Texas called Llanoite. Llanoite is a very
fine-grained granite with floating feldspar and blue quartz in it.
The blue quartz gets it's coloration from ilmenite inclusions. Llanoite
makes very nice gemstones along with being a nice decorative stone.
To the right is a pink granite sphere We have seen
many of granite's other colors used as gemstones too.
Granite is an igneous rock that is composed primarily of four
minerals. Magma cooling very slowly far under the earth's surface,
allows crystals of the four minerals to grow large enough to be easily
seen by the naked eye. These minerals are quartz, feldspar, mica,
and usually hornblende. However granite is not a homogenous
rock and it's composition varies depending on its location. Other
less common components give granite a wide variation in look and color.
The geological definition of granite is "any plutonic rock in which
the mineral quartz makes up 10 to 50 per cent of the felsic components,
and the ratio of alkali to total feldspar is between 65 and 95 per
cent." However you may find that commercial suppliers may not be so
specific. They may use the name granite on any of the other holocrystalline
quartz-bearing plutonic rock and of course these types of rock do
look like granite and may have many of it's properties.
Some Granite Properties:
Feldspar with a hardness of 6 and quartz with a hardness of 7, give
granite its exceptional abrasion resistance. Which makes granite so
useful as a commercial building material.
Some granites change relatively little with changes in temperature.
Which also makes granite a good choice for high precision applications
that require little change due to temperature.
Flexural strength, or the ability to resist bending force. Makes granite
a good material for load bearing applications
Granite is also resistant to many acids and other caustic chemicals.
So it is often used as a liner in commercial vats and such. This
also makes granite good for applications that are below grade in contact
with soil and water.
Some Facts and History:
Granite is the state stone for North Carolina
The term granite comes from the Latin root word granum, meaning "grain".
The state of New Hampshire has the nickname "Granite State"
Granite is quarried and used for many things on a world wide
The Four Main Minerals:
quartz is a common mineral that is found in many different types of
rocks. The chemical formula is Silicon oxide (SiO2). Impurities in
the rock at the time of formation causes the quartz crystal to produce
different colors. Quartz can be colored yellow, milky white, rose,
brown to black, blue and the best known color purple amethyst.
Feldspar is the most abundant mineral in rocks that are located at
or near the earth's surface. Feldspar can have a glassy white, blue,
green, pink or red crystals. When feldspars are exposed to the atmosphere
they weather easily. Clays are formed by weathered feldspar.
Kaolinite is the highest quality of the feldspar clays used by potters.
Hornblende is a mineral that contains magnesium, iron,
silica and aluminum. Hornblende is black, brown and green in color.
It occurs in crystals of many igneous rocks.
Mica can be clear, black, green, red, yellow, brown, purple lapidolite
and other colors too. Clear mica was named Muscovite because it was
found near Moscow, Russia. It was used as window glass in the Muscovite's
homes. Muscovite contains water which helps to make it clear. Biotite
mica is dark green to black in color because it contains metals such
as iron and magnesium.
As you can see the different colors produced by these four minerals
alone can give granite many different colors. Add other accessory
minerals and loosely associated types of granite and you get quite
an array of colors. Below is a link to a page that has dozens of different
granite colors. If you are interested.
If you want to learn all there is to know about granite. Click on
the link below. This is a site devoted to granite links.
types of granite information http://www.granite-hq.com