Mica is the name given to a group of silicate minerals that have silicon and oxygen as their two major components. The Mica family of minerals includes several variations based on chemical composition and characteristics. Three out of at least eleven are mentioned under out of the common variations.
- Biotite
- muscovite
- boromuscovite
The group formula including all member minerals:
K(Mg,Fe2+)3(Al,Fe3+)[(Al,Si)3O10](OH,F)2
Mica is a metamorphic mineral. The many variations come from the diverse ways it formed. Mica formations are associated with volcanoes and hydrothermal vents.
The most easily recognizable characteristic are the thin crystal layers. With many micas the sheets peel off in thin transparent layers due to mica’s perfect cleavage.
The crystal structure is monoclinic with a somewhat hexagonal crystal shape. These two characteristics are due to the structure of the atoms that make up the mica group.
Mica also has a brilliant shininess that glitters and sparkles. In fact the name mica is believed to have come from the Latin word micare which means “to shine.” Mica is responsible for the flashes of light in composite rocks such as granite, gneiss, and slate.
Mica is often used as an insulator in electrical applications, but it is also valued for collections and artistic applications.
You will "normally" find the mica like this in a stone, and not in a big sized mineral as the photos above, so here is what you will be looking for at the stone at gz. (Example photo under, not from gz)
To log this cache.
To get to log this cache you will have to visit and answer the questions which are related to the coordinates given the earthcache.
When answers are collected, send them to CO for verification.
You can log immediately after answers are sent CO. If there are any questions about your answers CO will contact you.
Logs without answers to CO or with pending questions from CO will be deleted without any further notice.
Please do not include pictures in your log that may answer the questions.
Questions
1. Answer the questions under by visiting the Coordinates.
A. How can you easiest identify the Mica?
B. The coordinates have leaded you to the King`s Cross area. Have a look at the wall, how much percentage of the mica would you say the stone contains?
C. What average size and shape are the black spots that you find?
D. Look at the different parts of the wall, do you think there are more spots to find from one part to another?
2. Take a photo of you, the group or the GPS from the location without revealing any of the answers.