Granite is the most common form of intrusive igneous rock. The mineral is granular in texture. The word "granite" comes from the Latin granum, a grain, in reference to the granular structure of the rock. Granite is an igneous rock with between 20% and 60% quartz by volume, and at least 35% of the feldspar consisting of alkali feldspar. The term "granite" is also used to refer to a wider range of igneous rocks containing quartz and feldspar.
Granites can be predominantly white, pink, or gray in colour, depending on their mineralogy. Green, black and blue colours have also been identified. Granite rocks mainly consist of feldspar, quartz, mica, and amphibole minerals, which form an interlocking, somewhat equigranular matrix of feldspar and quartz with scattered darker biotite mica and amphibole (often hornblende) peppering the lighter colour minerals. The colour of the granite mineral is usually based on the colour of the feldspar content. The quartz phase is usually a neutral colour. Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks.
At the listed coordinates you will find two granite samples that can be used as a field guide to distinctly different forms of the mineral. You will need to look at the grain structure and colour of both samples. A ruler will be a useful guide for your measurements.
Sample 1) - Top Rock - Examine the mineral structure; colours, grain size, texture.
Sample 2) - Bottom Rock - Examine the mineral structure; colours, grain size, texture.
From your geological inspection of the two field samples please make the following assessments. Send an email to the cache owner with your responses.
-Are both rocks granite? How do you know?
-Why is there a difference in the sample colours?
-What is the difference in sample grain structure?
The cache is able to be logged before confirmation is given by myself, but the answers must be sent within 7-10days of logging or your log may be deleted
