At the given coordinates is a rock formation composed of quartzite. As with any rock structure located outdoors, it is exposed to one or more types of erosion and weathering. The most common are wind erosion, wave erosion and precipitation.
However, the rocks located here are also being altered by another type of process known as oxidizing.
As a result of the aforementioned forms of erosion, the rock is broken down and kick-starts the oxidizing process. It is a process that takes place when elements that make up the rock structure come into contact with oxygen and a reaction occurs. This causes visible changes on the surface of the stone in the form of discolouration.
The discolouration can be varied depending on what the components making up the stone consist of. The most common types are iron components or bronze and copper components. The differences between the two are as follows:
Rocks with iron components:
The source of the iron in the stone is usually unseen on the surface but can be transported there in some occasions by water penetration from cracks in the stone. If no discolouration appears then the iron components remain on the inside of the stone.
The discolouration comes out as reddish-orange colour.
Rocks with bronze and copper components:
These components are already on the outside of the stone at the beginning of the process, so the discolouration forms by dissolved copper salts (from copper or bronze), which wash over the stone surface and then oxidize. The discolouration is streaked and follows a path from the origin of the source of copper or bronze.
The colours of this type can range from a light green to a dark brown shade.
Logging requirements:
Q1. Can you see any evidence of discolouration caused by iron components? What led you to that answer?
Q2. Can you see any evidence of discolouration caused by bronze and copper components? What led you to that answer?
Q3. Can you see any stones without any discolouration? What does this mean?
Q4. What form of erosion do you think "kick-started" the process of discolouration in the stones here? Is there any other reasons why?
Q5. Take a photo of you, your stamp or personal item with the rock formation in the background.
Please send answers via the Geocaching message centre or to my email, answers posted in the logs will be deleted.
You can log the find immediately, if answers are supplied to CO within 14 days, or you log will be deleted.
Happy caching!
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