Mica City Earthcache
In Colorado, United States
Size:  (not chosen)
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This Earthcache is located next to a road. The main coordinates refer to a safe place to park. Take care when visiting this site. This Earthcache come with a bonus...the opportunity to take a small mineral sample home to admire forever!
The story.....Millions of years ago, deep within the Earth’s crust, rock melted and was squeezed up into the overlying layers of rock. This molten rock material cooled slowly, forming veins of large crystals of the minerals quartz, pink feldspar, mica and other minerals. Many millions of years later, when these rocks were uplifted and exposed at he surface, geologists discovered them and named them pegmatites. In some places these can still be seen as fresh (unweathered) rock. In other places, the elements of weather and water, have reduces these just to crumbling mineral piles.In some places, these pegmatites have been mined to obtain some of their minerals.This Earthcache allows you to see two slightly different pegmatite veins.N 39 47.135 W 105 19.481Here, about half way up the road cut slope, you can find a relatively fresh pegmatite vien. It contains a number of minerals, the most obvious being the silverly mica (Muscovite). Mica is a mineral that forms in sheets, and these sheets make up a “book” of the mineral. The sheets can be easily peeled off the book and these sheets are transparent. Another mineral here is the black mineral tourmaline.N 39 47.140 W 105 19.476This site is a highly weathered pegmatite vein. The original vein has broken down to being just a pile of minerals. If you hunt around, you will find some very large mica books on the surface. Some here are almost 5 cm across.
To log this site, log in the dimensions of the largest mica book you can find and mention the number of people in your group! Also email the owner the answer to the following questions:
Both these sites are very close to each other. Why do you think that the two veins appear to be so different? (one so fresh, the other so weathered?) A possible answer is in the hint below.
Gur qvssrerag fvmr bs gur zvarenyf znl pnhfr gur qvssrerapr va jrngurevat.
Last Updated: on 07/29/2016 08:18:38 Pacific Daylight Time (15:18 GMT)
Coordinates are in the WGS84 datum