October
25, 2009
Wake County,
NC. Credit goes to Joe Moylan my friend and rockhound for finding this
great spot. This is an area
within a zone we identify as the
crystalline zone. Many of the crystals in this zone
are smoky
and have mica, rutile, and tourmaline inclusions.
An interesting characteristic of many of the crystals in this zone is a tessin
habit.
This means these crystals grew in higher temperatures around
500º C or 932º
F. The tessin habit is one in which the crystal has a wide
base that
narrows up along
the axis to a small point at the termination
forming a wedge shape.
|
|
There
was quartz everywhere
at this construction site. Most of the quartz was
from alluvial
deposits. There were
rounded quartz
rocks
everywhere. It was very peculiar, however, that we would
still find pristine crystals within the alluvium.
My guess is
that the area is one big
ancient mud slide where rounded quartz that
were exposed to weathering on the surface were mixed in with the
pristine ones that
were
gouged out of in situ dikes by the alluvium.
|
|
|
In
certain areas the quartz was very abundant yet absent of any crystals
or crystal faces.
|
|
Here
is an example of a crystal
that has obviously been deposited by the alluvium. The
rounded
edges, and the scratched
and chipped surface, indicate that it has been
in water where it has collided with other rocks to produce the
damage.
|
|
|
Here
is the damaged crystal after digging it up.
|
|
|
Here
is another alluvial find.
|
|
|
This
one has the tessin
habit shape.
|
|
|
I
saw something flash out of the corner of my eye.
|
|
The
fact that it was almost
completely buried made it look as though it were a deep smoky color,
but when exposed to the sunlight
it only has a slight grey smoky color. This is an example of
one of the pristine crystals that can be found within the alluvium.
|
|
This
is what Joe and I are now
referring to as an EOD or "edge of dike" piece. This is where the edge
of a dike has become crystallized and is usually covered with
m faces and sometimes terminations.
|
|
|
This
piece has two crystal m faces.
|
|
|
Just
before packing up I saw this
at the foot of the truck. It was just the m face or long
prism
face
of a crystal exposed flush with the surface.
|
|
|
Here
is the same crystal after extraction. This
crystal had a more normal habit. Another pristine crystal.
|
|
|
Here
was an EOD with terminations that Joe found.
|
|
|
Here
is a chunk of a water worn crystal found among the alluvium here.
|
|
|
This
is another water worn tessin
habit crystal found in this area.
|
|
|
Here
is an EOD piece I found with gemmy red rutile next to a mica book buried in the quartz.
|
|
|
Although very small, these crystals of rutile are a clear and beautiful ruby red.
|
