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.