North Table Mesa Zeolite Crystals

Looking across Clear Creek Valley to South Table Mesa from one outcrop of amygdalar basalt.

Zeolites are microporous minerals formed from aluminum and silica. Microporous means that their mineral structure has large holes in it, and this feature gives way to the usefulness of zeolites.  They can be used to purify water by the means of ion exchange beds that consist of zeolite minerals. For the same reasons they are commonly used in laundry detergents.

Although the zeolites found on Table Mesa aren't useful for purifying water, they are quite spectacular in their occurrence. The delicate and intricate zeolites from this locality are prized rare specimens that rarely occur together in other parts of the world.

They are found in the amygdalar basalts in this locality. Amygdalar simply means that there were holes (or vesicules) in the rock that have been filled in by some material, which is usually calcite or zeolites. If there were no material in the holes, it would be simply a vesicular basalt. The zeolites are reported occur in seven different varieties, but the most common seem to be thompsonite, analcite, chabazite, okenite and mesolite.

A cavity of thomsonite (the tan balls) that has been opened and exposed to weathering.

The basalts of Table Mesa are very difficult to break up. Attempting to break these rocks with a 16 or 22 oz. rock hammer would be rather futile, and its doubtful that your hammer would weigh the same after so much steel would get taken off.  Even my chisels would show a new imprint of the sledge's face after each impact, and the top of the chisel would mushroom out a bit and curl back with each hit. Usually, after smashing at a face for a few minutes with the sledge and chisel, you will get a fracture in the rock.

After a fracture has been propagated, which usually tends to be along the long axis of the zeolite pockets, you have to go and break out the ends of the fractures so that the rocks can be removed. Otherwise, they all fit in just like puzzle pieces that despite being loose do not want to be removed. After demolishing the rock to removable pieces, you get the pure pleasure of removing each piece and inspecting it for crystal-filled pockets.

This amygdule contains analcite, chabazite and thomsonite.

Sometimes you get nothing, and sometimes there are some large cavities. One indicator of finding pockets seems to be oxidation of the rock immediately surrounding the pocket. These little trails of oxidation can lead your hammer from one pocket to the next.

I believe this to be an okenite crystal (~2.5 cm) among chabazite (square white and clear crystals), this specimen (in-situ) was destroyed in the attempt to retrieve.

The zeolites are somewhat zoned, and in some areas different types of zeolites will be found more frequently. For example one area was characterized by large cavities of purely thomsonite. Other areas had cavities filled with thomsonite and analcite, and some contained purely chabazite. The amygdules in the thompsonitic area were commonly 6" long and 2-3" in height and tending to be stretched in a NW/SE direction. The largest was over a foot long and about six inches tall, with two separate cavities attached. It had however been broken out a long time ago and was therefore quite weathered.

Chabazite crystal showing its pseudo-cubic structure.

Also of note was the immediate change of color when the minerals are brought out of pocket. Within five minutes of exposure to air, my translucent green thomsonites had dulled to a tan coating outside. The more weathered thomsonites are completely tan. Also the chabazites, which in their cubic form resemble NaCl or salt crystals, are clear and transparent when first broken out but quickly gain a slightly white coating on the crystal after exposure.

An analcite crystal with thomsonite on basalt matrix,  the analcime is quite large for this locality(~1.5 cm wide)

Although a lot of effort oft results in cracked and damaged crystals, there is a technique to collecting these crystals from the pockets. A hard day's work may result in only one or two nice specimens, and sometimes the best ones escape you. If you decide to head up to Table Mesa, be sure to check that collecting is allowed before you go. Bring along some soft packaging to transport your crystals back to the car, because the jolting of carrying them can also damage the crystals.

Step into the freezer...

Basal ice from the GISP-2 core. This ice was the second to last meter before hitting bedrock, where sediment has been pulled up into the ice by the flow of the ice

      I spent most of my hours for the latter half of the summer at the National Ice Core Lab, where the current project was processing a 3.3 km long ice core that comes from Antarctica. That was about all that I knew going into the job. Later on, mostly through talking with the PI's and graduate students, I learned that there is much more to this than meets the eye. There have been more than 20 years worth of planning and work that went into this particular ice core.  The concept for a core from Antarctica was first conceived in 1989, when scientists were working on processing GISP-2, an ice core drilled from Greenland. Their work inspired curiosity to see if ice from the other side of the world would show them the same things that they had seen in GISP-2.

Ice Cores drilled over twenty years ago reside here at NICL in a -46 C deep freeze

As the cores are brought out of their tubes, they are measured and aligned according to how they were marked
in the field.

     These scientists, such as Kendrick Taylor and Mark Twickler, spent years obtaining radar profiles, mapping the bedrock below the ice, and looking at the rates of flow in the ice. When influenced by gravity, ice behaves fluidly, and actually flows. The motion is described in introductory geology texts as being similar to dropping pancake batter onto a hot skillet, where it pools and gains elevation where locally applied, but quickly flows outward. The data that the scientists are seeking would best be obtained from an undisturbed section, where they can be confident that mixing or motion of the ice is relatively low. After several years of research, they found a spot in the West Antarctic Ice Sheet, along a divide where the elevation was highest. The ice was thick there, and the bedrock profile showed that there was a large valley surrounded by two distinct and sharply rising mountains on either side. The hope is that in a dome or a divide, the motion of the ice will be low in the center of the feature. As they began test drilling to measure accumulation rates, the site took on its acronym, WAIS Divide.

The Horizontal Saw, also known as the H-saw, cuts two slabs of thicknesses 1.3 cm and 3 cm

     It is important to note here that the science of drilling deep ice cores was relatively untested, if not new,  at the point of conception. During the twenty years of planning to drill this ice core, they had to design and drill their own new drill, invent new instruments to measure the ice, and figure out schematics of living in the harsh ice covered land. They even went to such lengths as to figure out whether or not they could leave their human waste on-site (as it turns out they did, and they have figured that the waste pits will be stretched into a 1cm layer and pulled out to sea). Labs like NICL were constructed to store and process the ice cores that were being drilled from Greenland and Antarctica. The only other time that the U.S. had drilled for ice in Antarctica was at Byrd, a site that was selected because the numbers of its latitude and longitude sounded "nice", and without any consideration to radar profiles or disturbance of the ice. What they came to conclude after drilling and analyzing a core from that site is that folding and mixing near the bottom of the ice had stripped the core of its ability to represent correctly the ancient stratrigraphy, and thus held little scientific value.

   After they had worked out every detail of the drilling, they set out to antarctica for their first field season in 2006. They were only allowed one snow-cat to work with to construct all of their drill shelters and work areas. Drillers who were on the job for all season had quarters, visiting scientists resided in a field of tents specifically designed for the Antarctic. For five seasons of work in the field, they have 3,334 meters of ice core to show for their hard work. That's a hole that descends 3.334 km into the ice sheet. The amazing thing is that the drill only takes 3m of core at a time, and they have to pull up and lower the drill head into the hole each time. The wait times to winch the drill in and out while nearing the bottom of the hole were nearing 12 hours if I recall correctly. They stopped their drilling for fear of what is at the bottom, and for concern for the environment. There is a strong belief that at the bottom, near the contact with bedrock, the ice begins to melt, and sits upon a large body of water. If the drill penetrates the body of water, the drill fluid ( some nasty chemical) will be released into the otherwise untouched body. To keep the borehole open while drilling, they had to pour in some 200 barrels of drill fluid.

     The drilling teams only work during the North American winter, when it is warmest in Antarctica. Weather permits them a relatively short working season, because an ice breaker ship must be able to reach Mc Murdo, which acts a supply point for this camp and others on Antarctica.

The "ECM" or Electrical Conductivity Meter Sends an A/C
and D/C shock through the ice and measures the result

The resulting readout from the ECM

And so, after all of this effort, someone has to be able to use the ice to do some science. Every week at NICL, we would have a scientist give a talk. Usually it was a PI who came to visit, but scientists who were staying the whole summer also gave their talks. There are over nine PI's, or primary investagators that collect samples and run them to receive the data, which is in some cases then handed to another scientist for analysis. Scientists use machines that often times they have built, with complex functions and names like mass spectrometer and accelerated particle spectrometers. They look at a wide variety of things in the ice, including gases, chemistry, isotopes, physical properties, its electrical conductivity, and there is even someone who counts each and every visible layer within the ice. The level of analysis on the core is amazing, we heard from Kees Welton who looks at Beryllium-10 isotopes within the ice as indicating the amount of incoming solar radiation per year of accumulation. His data is correlating quite nicely with known sunspot counts that were visually confirmed and marked in history over the last few thousand years. Scientists used data from Greenland ice cores, other sites in Antarctica, and other outside data, and have proved the existence of several correlations. Most of the data that they analyze comes in the form of squiggly little lines that represent annual or event-based changes, much like the data from the ECM.


   The ice at the bottom of the core was estimated to be around 40,000 years old. This estimation is made from a proposed depth-age scale and from the actual count of the annual layers. One day, we took "snow" from the planer, a machine used to flatten one half of the ice core, and made some snow cones with grenadine and strawberry syrup. We chose the planer because it cuts from mostly the interior of the core where the exposure to the nasty drill fluid is least. I could never have imagined that a 40k year old snow cone could taste so good on a hot day.

The first cut of the chemistry slab is made on an ice core from over 3 km below the surface


The work that I did involved taking a 3 cm thick slab of ice, roughly a meter long and about 12 cm wide, and cutting out of this a 3 cm tall by 3 cm wide stick of ice. This stick of ice roughly a meter long would be shipped to Nevada to be processed with what is called a "continuous melter". This produces a constant flow of meltwater that can be tested as it is melted. By running this melt through several machines that measure different molecules, a large amount of information is obtained from these samples. During cutting, the bandsaws produce "snow" as if they would produce sawdust if cutting wood. This snow must be removed from the samples using a paint brush. This stick then had to be bagged, labeled, and its card correctly stapled onto it in order to be put into a box, which was put onto a pallet to be shipped to the PI. The remaining pieces also had to be bagged and sent to the pack-up station, which returned the remaining pieces of the ice core to the tube in which it came and stores them in the deep-freeze, for the possibility of future research. During the whole process, plastic gloves must be worn to prevent contamination of the core.

Red Rocks Canyon National Conservation Area, Nevada

We found it quite easy to visit Red Rocks Canyon National Conservation area. It was an easy 30 minute drive from the strip in our rental car, and we soon found ourselves on the outskirts of town entering into the beautiful landscapes and geology of the basin and range system. My Mom and I took the rental car and headed out of town.

There is the Aztec sandstone, a fine grained sandstone whose color has been altered by passing groundwater. Most usually it is the brilliant red of iron oxide, or a stark white, a color that usually marks the passing of oil through the beds.

There is a grey limestone that belongs to the Bonanza king formation.

Before even entering the park, we stopped at Calico Canyon, a popular spot for boulderers and climbers. We walked in a ways and took in the desert scenery.

At the bottom of the valley there was a conglomerate that had formed. One can imagine how desert flash floods moved these rocks into place. The clasts, or chunks of rock are made up mostly of limestone. The soft matrix is composed of fine grained sand from the sandstone.

The area was popular for climbing, and it was evident why. Tall, house-sized boulders had routes up their corners and the sandstone had cracks and pockets along the steeper faces that begged to be climbed.

Large scale aeolian cross bedding could be seen within these sandstones. This is typical of a sandstone, formed in a desert by the movement of dunes. The dunes' curved front surface is preserved as they move forward, leaving the small curves in the sand that deviate from the horizontal line. These lines are created as the movement of the dune erodes the sand in front of it into a flat surface, leaving the horizontal straight lines.

The area reminded me of the landscapes that Edward Abbey's Desert Solitaire spoke of. You could find places to hide here, caves hidden canyons, places in the harsh desert where nobody would come to look for you.

A pleasant sandstone den for someone. Nobody was home when we visited.

The area is also well known for its petroglyphs. This was found right along the trail, and I don't imagine that it is very old. Regardless of its age, though, it is neat. 

We then drove over to the Red Rocks Canyon area. A day pass was was cheap, only $7, and allows you to drive, bike or hike around a 13.5 mile loop. There are many roads turning off that would have been fun to explore, and the hikes you could go on I'm sure would be incredible. We, however got there at around 4:30 PM and they ask you to be in your car and driving out by 5 PM.

When I say that the sandstone is large scale cross bedding, I mean it. Here you can see just how large these are. This is the same sandstone as the red colored one, but it has had groundwater, and possibly petroleum passed through it. The areas of different coloration are created within layers of sandstone that are more or less permeable, so that the color is removed accordingly. This creates the lines that we can see with our eye from far away. Notice the person in the bottom right corner for scale.

We drove around, and wished we had more time to explore the trails. We then headed back to Las Vegas, where you could buy a tall can of PBR or Coor light for an outrageous price.

Or just gamble and drink for free.

Sluice Concentrates

If you are using a sluice box, at the end of the day you are left with black sand (which is much heavier than the quartz and feldspar sands which are light colored) and hopefully gold in your sluice box. Every attempt is made to easily remove most of the gold next to the river, but there is always some left in the sands and so you bring them home. Thus the predicament that most prospectors are faced with is born, fine gold and black sands.

The combination of the two can be a headache, especially if all you have to work with is a pan.  When I started prospecting, I bought a spiral panning machine that separates gold or heavy materials out, called the Desert Fox.  I came very close to selling the thing, because I was under the impression that it didn't work at all. I would run all of my concentrates at different angles and water speeds and get nothing but black sand, no matter what I did. It took me a while to figure out that there wasn't actually any gold in the material I was running(duh).

Once I actually started bringing home fine gold in the concentrates, the Desert Fox really showed its true potential. I'm now a solid believer that it can separate gemstones or any denser material for that matter, and it can do so quite efficiently when set up proper. Its ease actually allows me time to do work more while I'm at the river, instead of panning out my concentrates where there is water.

My process goes something like this:

When I run material, I use my snifter bottle to pick up gold I can see on the indicator matting. This gives me a peace of mind that the gold isn't going to travel further back into the sluice, where it has a greater chance of getting washed out. Also, I have the bulk of my gold (or so I hope) to pan out at the end of the day, but its always a manageable amount of black sand. Everything else sits in the sluice until a clean-up, where I dump the whole sluice load into a dedicated concentrate bucket.

This represents two days of sluicing. The concentrates come from Cache Creek BLM area by Granite, CO

When I take this home, the first step is to classify the material through a set of screens. The screens that I use are 1/4", 12, 30, and 50 mesh. The mesh size is measured by the number of openings in a linear inch.  I dump the black sands on the screens that are set up on a bucket. I take another bucket full of water and slowly pour it through while shaking to classify it.

All of this material was removed using a magnet. Magnetite retains the magnetic orientation of when it
crystallized due to its atomic structure, and will retain its magnetism for a very long time.

Once classified, I run them in the Desert fox starting with the material between 50 and 30 mesh, and move to the coarser material. Although the machine claims to be able to separate clean gold, I haven't been able to do so without feeling like I have lost some. I always set it up so that it takes a bit of black sands too, that way I can be absolutely sure I have gotten everything I can. When the material is well classified, and with the aid of a magnet, panning the gold from the black sands is a breeze and takes only a minute or two to get clean gold.

Some processed gold from the Desert Fox

Desert Fox doing what it does best.

I'm not sure that this machine can competently separate the fine, fine gold that slips through the 50 mesh screen, so I have been saving this material in a bucket for quite some time now. Ideally, I would like to run it through the Fox and then through a Blue Bowl, because I have heard they are better for this sized material. A Blue Bowl uses spinning water that empties into a hole in the middle of a bowl to allow the fine gold to separate. I would also be willing to invest in screens in the 100, 200 and 300 range, because I'm sure that there is a lot of gold in there that is otherwise practically inseparable.

I almost didn't run my 20+ material through the Desert Fox, because I thought that it might be easier to hand pan. I'm very glad that I did, though. When I was not expecting much gold at all from this material, the big guy on the right jumped out and ran up the spiral. It is my first nugget to register on a scale, weighing in at a massive .1 grams, making its worth around $5 currently.

For two days of moving around 15-20 five gallon buckets of dirt each day, its not a very good paycheck.
For spending two days outdoors, in the sun, and next to a creek with a huge smile the whole time, it is priceless.

Abandoned fluorite mine of Jamestown, CO

The Jamestown and Ward region, located up Lefthand Canyon endeared years of mining success during its booms, and like all other mining regions, misfortune and busts. The region produced gold, silver, lead, copper, and fluorite (then called fluorospar). Low grade fluorite is used as a flux in the melting of iron to increase fluidity, and so the region boomed during both world wars. Now, only a few year time residents and summer cabins remain in this area, but the aftermath of the mining is evident. Holes are dug into the side of the hills everywhere, and the yellow dirt can be seen pouring out onto the hills in many areas. These yellow rocks are sulfide minerals, which are frequently associated with veins of precious metals that have been deposited hydrothermally. These sulfides, when exposed to water with higher surface area react to form hydrosulfuric acid.

Chemically,

 2H20 + S ---- 2H2S +02

The additional oxygen molecule often proceeds to react to form carbon dioxide. The water that runs off  is then considered acid mine drainage. This region has a huge problem with this, and there are some mines designated as superfund sites that need to be cleaned up. One attempt to remedy this has been to put bags of limestone below the tailings piles, so that it will hopefully absorb the acid before it reaches the stream.

My mineralogy teacher, Joe Smyth, took us on a field trip up left hand canyon, and showed us some pegmatites, high grade metamorphic rocks, and then this fluorite mine. The few minutes we spent there wasn't enough for me, I have been back a few times exploring the area. The fluorite there is a pretty purple,  but doesn't occur in very solid crystals. The mine was originally a gold mine, but later was further developed for its fluorite.

The main pit. Fractures and fisures have been stained black by manganese bearing waters.

The pit was dug directly into the hillside, and the walls are about 60 to 80 feet tall. An old headframe sits on what used to be the side of the hill, and above the tailings pile. The tailings are a fine yellow dirt, that erodes easily into steep slopes, exposing the iron and wood fragments that make it so uninviting. The interior of the pit is also filled with this fine tan-yellow dirt, but no tetanus shot required.

Looking down at the side shaft. Pick axe for scale, ~3.5 ft long.

A small hole dug down connects through to the main pit. Its really quite tempting to climb down through it, but this is probably ill-advised with the unstable condition of the rocks. This shaft drops about fifteen feet before connecting horizontally with the main pit, still about forty or fifty feet above the bottom of the pit.

Quartz crystals in matrix.

                                                                                                                                                            










Some purple fluorite can be found in the walls and floor of the pit. It is quite rotted and is often found as a purple powder. Crystals here are rare, but I have found weathered cubes in some of the bigger boulders on the floor of the mine. Fluorite has a cubic crystal habit, and can form octahedrons, cubes, and plenty of like variations. On this trip, I wasn't looking for fluorite. I visited some outcrops above the mine and found some quartz crystals exposed from weathering on some fissures. They are a grey color, and embedded in matrix. I managed to chip away a crystal or two.

Two small, loose crystals.

Clear Creek Gold

With the few days left I had of spring break, and after being chased out of the central mountains by a huge storm front, I wanted to dig for some gold for a few days.  I headed out to Clear Creek early one morning to look for a place to dig. I was hoping to find some coarse, big gold that I knew was out here!

A wildfire in the gulch to the North had been spreading quickly, and on my drive up I witnessed some of the power and proximity of this fire. The canyon is curvy, and the hills on the side are steep. As I drove along on the road, without any cars around, I noticed that on the top of the ridge the trees were actually on fire. A 20' pine tree was a ball a flames, and the ground around it had 4-5 foot flames all around. It was absurd to think that the forest was burning right there so close to the road. I got another mile or two up the canyon to where I spotted a Jeep that I recognized as a man, David that I had met one other time before on the North Fork of Clear Creek.

I parked and walked down to where he was working. After doing a little sample panning, I decided on a spot on the upper part of this placer bar behind a large rounded boulder. The spot was showing a few specks a few feet down, but nothing too promising. I wasn't too far from David, and we would chat every once in a while about the history of the area, and our theories on the gold. After an hour or two, police sirens on the road caught my attention. A Jefferson County sheriff was yelling at us to leave, because the canyon was closing. We both began hurrying to clean up and pack our stuff back to our cars. By the time we could pack our stuff up, 3 other officers stopped and yelled at us to leave. David asked if I wanted to go  to his hole up the creek and dig there. He said he had been finding small nuggets, and guaranteed that I would too if I came with him. With my doubts, I followed him to his spot (which he asks I do not share the location of) where he had quite a large hole dug. Surrounding these boulders buried deep in the river, he said he had been getting the gold.

I began to dig, which wasn't easy because the hole was so deep and the footing precarious. My thigh-high waders were about an inch away from being filled in with cold, cold water, and in late March, the air temperature isn't quite optimal for swimming. I sluiced out all of my material, without seeing any gold that I could get too excited about. As it got dark, I cleaned up my sluice, and as I washed the top material into the bucket, there it was!
 
A Nugget!

My first decent sized piece of gold. It hasn't traveled very far, and is almost wiry.

Another day's work. Its not easy, but nobody said it would be.

A piece of gold that I could pick up and hold. I got very excited, and finished cleaning up with a huge smile on my face. We agreed to meet there the next morning, and continue digging. We did so for the next three days, and ended up finding some good gold.

In search of Barite and Topaz

The Granitic Tarryall Mountains, power lines and road signs.

   Some people choose to go to Mexico for spring vacation. Some people choose California, more choose Las Vegas, and more still like to take their break in Moab, Utah. Myself, I like Colorado.

I began my vacation by driving to Tarryall, to look for some Topaz that was rumored to be around these parts. The granitic mountains here are very pretty, and the scar of the massive Hayman fire that ripped through here years ago is beginning to heal. I spent the afternoon hiking the region accessible from Spruce Campground (or something like that), and looking at a lot of granite. Topaz crystals form in granite pegmatites, which are known to be found (in abundance) in the region.

A rundown on pegmatites:

      As a large body of granite is cooling (granite by definition cools very slowly), it is changing from a liquid to a solid. Large crystals are forming as the rock cools, but in a certain sequence of the available minerals. All materials melt at different temperatures, thus they will crystallize and come out of solution in the opposite order. As the rock is cooling, minerals that remain in solution tend to be rare earth minerals, and concentrate along with quartz, which has a very low melting/crystallizing temperature and form pegmatites. Beryl (aquamarine), Tourmaline, and Topaz are all examples of the gemstones that can form from the extremely slow cooling pegmatites. 

A perfect example of a meandering river, with some geese
standing on rocks most likely moved by glaciers

I found one pegmatite that had been excavated. The opening was 20' wide and 30' tall, with very steep sides. Contrasting to the entire mountainside, the walls were made up entirely of quartz. I carefully examined the walls for any sign of pockets where the crystals could form, but didn't see anything. The tailings didn't look too promising either, but I figured if somebody had come all this way to dig out that much rock, they had ought to have a darn good reason. I camped that night by the Colorado Topaz Mine, where an old screener box was sitting, without the screen. It looked like they had been digging around all of the large granite boulder sitting through the camp area. The nearby Colorado Topaz mine  is a  placer deposit of gem-quality Topaz, and has been a very sound producer. In the morning, I dug up a bucket of my own material to screen out when it wasn't freezing. 

The hole in which the barite was found. For scale, the green
screen in the upper part of the picture fits snugly inside the top of
a 5 gallon bucket. It was kinda nice to get out of the wind.

Driving on to the next stop, a barite crystal locality, I soon found myself in someone else's hole. Barite is a heavy mineral used for oil drilling as a thick mud, but occurs in CO in a rare blue variety. They occur in sedimentary rocks, and a formed under low pressure and temperature. They had dug down to the crystals, and must have either had their fill or gotten tired, because they left them exposed in the bottom of the hole. Sure, it wasn't the best hole for proper digging posture, and there wasn't much room to move limbs about, but it gave plenty of license for creativity.  After spending some time cleaning the specimens up, some are quite pretty, and I hope to return soon to dig out some more. The crystals will absorb UV light throughout the day and become more and more blue, so they are very pretty in windowsills.

Here the elaborate crystals are exposed in a mud filled pocket.
The bulk of the mud easily washes away, but the cracks are
filled in with mud, calcite, and iron oxide, but this is all
 easily dissolvable in a strong acid.

In the same day, I drove to Nathrop by Buena Vista, and in the whipping winds and ocasional flurries of snow went searching for garnets and yellow topaz that was rumored to occur there. It was so cold, so I practically ran to the top of the mountain that is of a certain rhyolite that is quite distinguishable. I looked all along the way, but only found one small crystal that I think has a chance of being a topaz because it is squarish and yellow/brown. I found out later that you need to split lots of rocks to find the gems, which I didn't split a single one. Regardless it was beneficial just to look at the geology of the area that they occur in, and now I know just where to go and what to do when I return this summer.

After and exhausting two days (and with a large oncoming storm front) I drove back to Boulder, ready for warmth. When I got there, I sat down, and wished I was still digging in a hole somewhere.

I guess thats just how it is.

A Weekend on the Platte

One day's worth of work. Note the piece of dull gray platinum.

 After taking advantage of the good weather and heading down to my new favorite placer deposit by Commerce City, I found myself digging in the sun, and finding some gold too. I had located this spot off of a website by a guy who lives in Denver and sells prospecting equipment. He was testing out his products at this placer and made quite the discovery.
     Turns out though, its not that new of news. These deposits are the same as the ones that the first pioneer dipped their shovels into on their way to California. Most prospectors didn't think much of it, and headed west. When they didn't find their fortunes in California, they thought back to the Platte that they found that fine gold in. From these same placers, they worked west into the mountains and found all of the lode deposits. They were again mined during the depression, which in my opinion strikes a bell will all of the digging has ocurred at this spot.

The second day's work. This is just what I picked up from
pans and the sluice, even more is in the concentrates!

        Fine gold is in abundance at this spot, and found about 6 inches below the surface. Gold is found in all areas of the placer, but the larger pieces are concentrated in a straight line. Test pans revealed on average 2-3 decent pieces and about 15-20 very fine colors to the pan. One day I was out I only classified my material to 1/4", and the other 1/8". When I classified smaller, I found my sluice worked much better, and my overall gold recovery was better, but this could also be because I dug along the "gold line".
 It was fun to finally get some gold! I estimate about 1.5 grams from the weekend, but I still have to run all the sluice cons through the desert fox, and then clean and dry all of the gold. Lots of work, but it is worth it!

Field Geology: A cold day for a stromatolite

  In my Field Geology class at the University of Colorado, we are learning to create geologic maps. We have been using our Brunton compasses (not just your everyday compass) to make measurements about the rocks. We look at things like how thick the section of rock is, what kind it is, where it is pointed, and which way it "dips", which is the direction that a rock unit is sloping downward. Making both quantitative and qualitative observations, and gathering LOTS of observations, we should be able to produce a geologic map of the region that describes the history and rock types of that area.

The class listens as our professor, Lon Abbot, describes a brief history of the stramatolite

Today, we were just practicing making these measurements, because the details of these procedures raise lots of questions in their application and accuracy, so that we can be prepared when we head into the field. The weather forecast had given a high of 45 degrees, and it may have reached that in the morning, but by noon when we head into the field it was getting nasty and cold. A storm coming into the region promised 7" of new snow and a high of 11 the next day, so the mother nature was feeling tempermental. 

There was plenty of snow on the ground as we took notes on outcrops of varying rock types and ages. We followed a hiking trail that took us through the depositional history of the front range of Colorado, getting younger and younger from the Pennsylvanian aged Fountain formation (a notable red rock characteristic of places like Red Rocks Ampitheatre and Garden of the Gods) to rocks that had been recently moved within the last few million years.

A pattern characteristic only of
stromatolites.

The particular rock that we are looking at in the picture is a stramatolite. It has close, thin wavy bands on its side, and these differ from ripple patterns in the fact that they are not symmetrical or of a constant amplitude. The rocks at first did not appear overly interesting. We had examined several rocks from this formation when we came upon one which was different. One person within our group correctly identified it as a stramatolite. Our professor Lon was explaining to us that these stramatolites are the oldest organism that we have on fossil record, and they consist of bacterial mats that grow in humps together. This first organism was quickly outdated by other organisms, and later became a food source for some creatures. The theory is that stramatolites are only preserved in fossil record in areas that were of high salinity or otherwise unfavorable for creatures to eat them. They grow only in areas of calm water movement, but could grow in either freshwater or saltwater environments. The other rocks (which did not have stramatolites) we had been looking at surrounding it further indicated that these organisms flourished in one particular spot.

For what at face value had appeared to be a quite dull rock, its history is actually quite remarkable, and it turns out that these characteristics are specific to only stramatolites, and even more can be interpreted about the environment that those rocks were deposited in. In creating our geologic maps, we are being taught to rely on our ability to piece together clues that lead to the complete history of those rocks. Our next project is to begin mapping a decent sized chunk of land, Mt. Sanitas in close proximity to Boulder.

Gold

It may not look too big, but the biggest piece of gold in this pan is the largest I have found to date!

    I headed up to the North Fork of Clear Creek Canyon this last saturday for some snowy prospecting. Missing out on a powder day at the resorts, I hoped that prospecting might have me bringing back some gold. I spent about six hours digging and sluicing only one bucket of bench deposit material. Bench deposits were left on the sides of the river, way back when the river had not eroded down to its current location. These deposits usually weren't worked by the old-timers, and sometimes can have lots of gold left for us! I spent all six hours on this day digging and sluicing one ONE bucket of material! My sluice wasn't set up right, and the riffles would pack full of fine sand and clays. I was watching my gold come in at the top, set up in a riffle, and walk its way right down into the river bed. For some reasoning, I didn't want to run a clean up and re-set up the sluice twice, I already had once because I had felt it wasn't working right, so I kept running material through and watching the gold exit.  My first clean-up held two small flakes, right on the lip of the sluice after I pulled it out. The next one held a slightly bigger flake, and then the biggest flake (almost a nugget?) that I have found to date. Don't get too excited, its still very small. But I am excited, I feel that if I dug the same material with a well-working and bigger sluice, I could probably extract a decent amount of gold.

Winter Prospecting

      Even with the cold 13 degree temps, the gold bug bit and I took a sick day from my physics class. My field geology class had already been canceled for inclement weather, so the day was wide open. Leaving around noon, I hurried up Clear Creek Canyon with sluice, buckets, bar and shovels in tow. Arriving at the locality I had been e-prospecting, I found that it was north facing, coated in snow, and had already seen the most sun for that day. Delightful! To add to the elation, the spot was just downwind of a sewage treatment plant. It looked like there had been lots of past digging in this spot, behind boulders mainly, so I found myself an undug boulder at the top of the placer and started chipping away.
     Well, the ground was frozen solid. So I started chipping at the frozen creek, and finally worked up some water. Pouring this on the ground, I hoped, would thaw it enough to be dug, but it just froze within seconds and made a nice little pool of ice.
     Scratching that idea, I started pounding the ground with bar and shovel, and managed to work out about a half bucket of material. The material came off of a clay layer about 4 inches down that was frozen solid. Scraping the clay was just like curling very hard chocolate, but you would see gold flakes as they were pulled out! Curiosity finally got to me, and I took a handful of the material and panned it quickly. This one handful had about 9 or 10 finds, well worth the time.
     The hard work was keeping me warm, but after about two hours with almost a half-bucket of material and no water with which to sluice, I packed up and headed home. At home, I quickly set up my desert fox-a machine like an archimedes spiral that separates gold and attempted to classify the material, which just separates it all by size. The water froze in the classifying screens, and left me soaked in muddy water and with cold hands. The sun had gone down by then, and the water in the wheel also froze on the desert fox, so there wasn't a chance. I packed it up and went inside, cold and disappointed.

Calcite Crystals and Caves

After doing much probing to find information on the Owl Canyon calcite locality, I didn't find much. Well, a few things
    1. A book - The Rockhound's Guide to Colorado by Kappele that listed this as a locality and not much detail about where to find or look for crystals.
    2. A friend, telling me that his dad had once found crystals in this spot.
    3. Best of all, a cave survey detailing a cave in this exact area, describing the walls of a cave that were literally lined with crystals. Now that's promising!

    After some trailfinding and bushwhacking, I made it to the outcrop, where Colorado Lien had previously  dug some pits down to unexposed limestone. From what I understand, this company mines the limestone for a supplement in cattle feed.  The limestone that the crystals occur in is the Fort Hays member of the Niobrara formation. I examined, smashed, and overturned lots of boulders, and searched directly on the outcrop for calcite crystals.

As for the cave, it descends probably 20' to 25' vertically and the horizontal is probably close to the same. I didn't quite reach the end, claustrophobia kicked in when things got tight, and being alone didn't help, though I am sure it just right down around the corner. The description, though, is quite accurate, the walls protrude in triangular calcite crystals, many have been smashed away. The degradation of the cave is evident, and sad. A small piece of plastic was in the main chamber, and I promptly found room in my pocket for it. As to the exact location of this cave, that information is only for those who are trustworthy. Preserving this cave is very important, and the more people that know about it (who will not take care of it) severely decreases the time that we will be able to enjoy it.