What is granite?:
Granite* is a common type of felsic intrusive igneous rock. Granites can be predominantly white, pink, or gray in color, depending on their mineralogy. The word "granite" comes from the Latin granum, a grain, in reference to the coarse-grained structure of such a holocrystalline rock. Strictly speaking, granite is an igneous rock with between 20% and 60% quarts by volume, and at least 35% of the total feldspar consisting of alkali feldspar, although commonly the term "granite" is used to refer to a wider range of coarse grained igneous rocks containing quartz and feldspar.
The term "granitic" means granite-like and is applied to granite and a group of intrusive igneous rocks with similar textures and slight variations in composition and origin. These rocks mainly consist of feldspar quartz, mica, and amphiboleminerals, which form an interlocking, somewhat equigranular matrix of feldspar and quartz with scattered darker biotitermica and amphibole (often hornblende) peppering the lighter color minerals. Occasionally some individual crystals (phenocysts) are larger than the groundmass, in which case the texture is known as porphyrityc. A granitic rock with a porphyritic texture is known as a granite porphiry. Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks. Petrographic examination is required for identification of specific types of granitoids. The extrusive igneous rock equivalent of granite is rhyolite.
Granite is nearly always massive (lacking any internal structures), hard and tough, and therefore it has gained widespread use throughout human history as a construction stone.
Granite has a felsic composition and is more common in recent geologic time in contrast to Earth's ultramafic ancient igneous history. Felsic rocks are less dense than maficand ultramafic rocks, and thus they tend to escape subduction, whereas basaltic or gabbroic rocks tend to sink into the mantle beneath the granitic rocks of the continental cratons. Therefore, granitic rocks form the basement of all land continents.
How to log this Earthcache:
Send me your answers BEFORE logging the find.
In order to claim the find, send me an email using the link just belot the Earthcache title with the answers to the following questions:
1) Describe the surface of these boulders? What color is it predominantly? What other colors do you see in it?
2) Describe the texture of these boulders? Do they feel smooth or rough to the touch?
3) Do you see evidence of quartz present in the composition of these boulders?
4) Estimate the thickness of the veins that you see in the central part of the middle boulder and tell me how wide they are.
5) (Optional) Post a photo of yourself or your group near the boulders, but do not show the text on the metal plate. This is not required to claim the find.
Send me the answers to these questions along with the GC code and the number of people in your party (with their geo nicknames) BEFORE you claim the find. I reserve the right to delete your log if you log the find first even if your answers are correct when I get them. I'm pretty lenient with every other requirement except this one.
*Source: Wikipedia
This is the final of my "7 Earthcaches in 7 States on 7 Days" inspired by our move to California from Florida. We wanted to commemorate our transcontinental drive from coast to coast in a way that would last, and w could not think of a better way to do so than to provide educational experiences through Earthcaches. Thank you for visiting!