Upper Rock Creek - Montgomery County MD

Here are a few sample pics from Upper Rock Creek in Montgomey County MD.  All samples were taken from a stream bed located about 1.5 miles NW of Lake Needwood in Derwood MD.

Quartz with Ferric Intrusion

This is a very clear transluscent sample of the local quartz in Rock Creek.  This particular piece was broken from a rounded stream cobble that showed a dark spot on the surface.  The spot turned out to be a dark black crystaline structure with the same luster as the quartz.  As I am still in the early stages of learning, I am not sure exactly what this black spot is.

Quartz with Magnetite (?) Intrusion 1

Quartz with Magnetite (?) Intrusion 2

Two images of a Small Quartz Cobble Broken to reveal what I believe to be Magnetite Intrusions.  The top image is with room lighting (flourescent) and the bottom image is with camera flash.  There are multiple crystal structures going on in this sample and the coloring varies dramatically.  The quartz in the lower left side of these pictures has a very golder iridescence.  The small light spot to the right of the middle magnetite has a green tint to it as well.  Possible evidence of gold and copper?

Ferric Sandstone of fine Quartz

This image is of a very compact sandstone with ferric (iron) discoloration and minor intrusions.  Formed primarily of transparent clear Quartz grains, it also exhibits some fine, clear, golden mica flakes.  The stone had serious ground discoloration and the interior was darker where part of the stone rested in sand/gravel bed of the stream.

Ferric Quartz with Magnetite (?) Inclusion

This sample is another piece of the Ferric Quartz from above.  This section of break shows a nice nearly transparent crystal form to the right side.  Directly beow that is a section of finer crystal forms with a golden iridescence.  To the left of the sample is the magnetite intrusion.

Ferric Quartz with Finer Golden Iridescent Crystals

This smaller sample of Milky Quartz is translucent with Ferric discoloration.  The center of the sample has a much smaller crystal structure that is highly golden in sheen.  The golden sheen progresses to the outside of the sample in the left side of the image.






These are but a small sampling of the rocks found in Rock Creek and broken to reveal their interiors.  Once I have a better system in place, I will be taking much more detailed images at higher magnification and brighter lighting to better display the crystal structures them selves.  I have about 20 lbs. of additional samples to take home to process.