Granite is a common type of igneous rock. Igneous rock is one of the three main rock types , the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava, which then forms crystals which make up the rock. Granite is formed of crystals, of which some can be described as phenocrysts. Igneous rock forms by crystallisation either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.
Crystals within granite can be described as phenocrysts. Of which there are varying shapes.
Their descriptions can be found below:
- Tabular - a term used to describe crystals with rectangular tablet shapes.
- Equant - a term used to describe crystals that have all of their boundaries of approximately equal length.
- Acicular - a term used to describe crystals that occur as long, slender crystals.
- Prismatic - a term used to describe crystals that show an abundance of prism faces.
In order to log a find against this EarthCache, you will need to send your answers to some questions via my Geocaching profile or through the Messenger facility.
1) The stone of the War Memorial is granite. Please tell me the size of the largest phenocryst you can see and the size of the smallest visible one you can see on the first step of the Northern side.
2) How would you describe the phenocrysts in the first step on the Northern side; from the four classifications above?
3) Is this the same on the second step? Please explain your answer.
If anybody would like to expand to this series please do, I would just ask that you could let Just-us-Two know first at email@example.com so they can keep track of the memorial numbers and names to avoid any duplication. OR (If your cache page is in html then please copy the text at the bottom of this page instead) If you could let us know the GC number when the cache is published that would be helpful. We will then add it to the bookmark list.