The mineral columbite-tantalite contains the metals tantalum and
niobium. Both of these metals are classified as incompatible
elements which means that they do not readily form or become
constituents of common rock forming minerals. The ultimate
source of this mineral is from specific types of felsic plutonic
rocks and pegmatites. Ferralitic weathering in the tropics
releases columbite-tantalite crystals from their rock matrix and
subsequent fluvial processes can concentrate it in placer
deposits. Placer deposits lend themselves to low tech, labor
intensive mining methods that many of the poor have access to.
Tantalum has desirable material properties for the manufacture of
small but powerful capacitors used in cell phones, laptops, and
other battery powered small computing and telecommunication
devices.

Until recently the world supply of tantalum was satisfied by a
few mines. The price of tantalum was set by long term contracts
between a few producers and refiners. Several countries
including the US held strategic stockpiles of tantalum as a hedge
against interruption of supply in wartime. Over the course of
the last few years, this stable supply chain has broken down to
some extent and the supply-demand situation has become unstable
opening up opportunities for new players to produce this mineral.

Next month, I am travelling to West Africa to develop a
columbite-tantallite exploration program. This is a great
opportunity to incorporate a new instrument into our already
robust field data acquisition system. I will be using an
Innov-X-Systems Omega handheld XRF linked to a TDS Recon runnning
ESRI ArcPad software to evaluate field samples in real time.

Preliminary samples have tested at up to 47% tantalum and 17%
niobium. Textures and luster suggest two sources in the area we
will survey. Medium to coarse sand size, well rounded metallic
grains clearly originate in heavy mineral accumulations in an
alluvial setting. Even more exciting are medium gravel size,
sub-rounded euhedral to broken euhedral single crystals of
columbite-tantalite that are found as a surface lag over
lateritic soil. The latter have a thin veneer of oxide coating
which along with their angular shape suggests derivation from a
nearby bedrock source.

Alluvial columbite-tantalite grrains

Large columbite-tantalite crystals from soil

We covered another thousand square kilometers of the Sahara one sq km at a time taking eleven hundred radiometric and geochemical measurements in a mere fourteen days. Our mixed Touareg, Arab, Fulani, and American crews quickly became well honed technical teams despite the fact that two of our three teams did not share a common language. It keeps useless chatter to a minimum if no one in the truck understands what anyone else is saying. Most problems can be resolved with creative mime, drawings in the sand, and a smile.

Now for the wildlife report. I jumped two Golden Jackals in a rocky canyon and was within 15 meters of their napping spot when they broke cover. These two were about the size of coyotes and their coats where a superb match for the dull red brown of the terrain. Bird life included numerous African Mourning Doves, and Spotted Sand Grouse, a Houbara Bustard, two Pharaoh Eagle Owls, Egyptian Vultures, a stork(?), Pied Crows, Black Kites, Barbary Partridges, and numerous assorted tweety birds. I surprised two Fennec Foxes intent on excavating a new den. When they realized we were close they could only hunker down and hope we couldn’t see them. Their massive ears were sticking out of the hole furiously turning like little radar dishes before they bolted for the bush. One of our local Arab workers told us a male lion had been seen in a rugged range of low hills just a few weeks before we passed through these same hills. Apparently this critter had a taste for donkeys. Miles reported a massive white scat in the area which is probably about as close as we will ever get to seeing a lion in the Sahara. Our military escort tried to shoot a large snake but it is not clear they could hit it at such close range before it dissappeared into the bush.

Speaking of our security escort, I got a chance to plant a Bread not Bombs sticker on their machine gun. If you have been through Durango Colorado, you might know of Bread, the best bakery for miles. I carry some of their pacifist stickers just for the fun of putting them in unlikely places like this.

My ear protection is not to damp the sound of machine gun fire. I doubt if that WW-II relic would get two rounds through the chamber before jamming on the grit. My pal Boubacar (on my right) and I had a shooting match with his pistol, a 9mm semi-automatic held together with duct tape he borrowed from us. Seems neither one of us could hit a bottle at 25 paces with one shot. I guess we’re both out of practice. I think any bandit attack would have to be scared off by the noise. That is if these guys could ever chamber and fire more than one round. After the embarrassing snake shoot and our target practice, it seems unlikely they could actually hit anything. I guess it makes their new Bread not Bombs sticker even more relevant.

Stratamodel’s 2009 radiometric survey schedule is beginning to fill up. We expect to return to Niger in January and remain through April. Our North American schedule will include a return to the Colorado Plateau in June. Contact Stratamodel to discuss how we can help your exploration program in 2009.

We are in the process of upgrading our 3.2 cubic inch gamma probes to 21 cubic inch NaI(Tl) gamma probes from Rexon Components. These new probes are far more sensitive to low level gamma radiation and when paired with our URSA II multichannel analyzers will improve our already excellent ability to collect detailed gamma spectra from shallow soil boreholes.

After another round of programming, our digital data logging system is better than ever. This ESRI ArcPad based system implemented on TDS Recon and Nomad rugged field computers speeds data entry and eliminates errors during data transfer among computing platforms.

Custom ArcPad data entry form on a TDS Nomad

We are also developing a new series of soil augers for deeper, easier, soil penetration while retaining the light weight and rugged design that enables a Stratamodel crew to take as many as a hundred soil samples per day..

Lightweight soil auger

All of these improvements and innovations will keep us at the forefront of exploration and environmental soil sampling in 2009 by improving crew productivity, reducing errors, and lowering our detection limits.

Deploying a radon detector.

Our field camp was well managed by Niger Uranium staff, daily feeding our group of about thirty, three hot meals of typical Nigeriene food. It doesn’t take long to get tired of a dinner consisting of chopped goat and rice or couscous especially when the chili powder runs low. Breakfast was rice cooked in powdered milk and sugar. We could vary that by adding cocoa powder every other morning. Our field lunches were plain pasta with a few chunks of chopped goat parts. Water for cooking and washing came from an artesian well about 40 km away. Bucket baths with this very soft water usually left us with a soap film that we just couldn’t seem to get off.

“Allah Akbar…”, the pre-dawn call to prayer beautifully sung by one of the crew is our alarm clock each morning. After a quick breakfast each team loads its trucks with radon detectors, steel wire, fluorescent survey flagging, plastic cups, field computers, gamma spectrometers, and our soil augers for the day of drilling and sampling ahead. Our escort of 30 soldiers in their three ‘technicals’ (Toyota pickups with heavy machine guns mounted in the beds) join us for the trip out to the soil grid. After a wild high speed cross country ride over mudcracked dry pans, gravel covered low hills, and across numerous dry wooded stream courses we get to work drilling a shallow hole and collecting our data every three to six minutes for the next eight or nine hours. The days start cool and clear but by noon it is 90-100 degrees and the November sun beats down on us until late afternoon. We consume three to six liters of water chased by several beers back in camp to stay hydrated. The rough terrain takes a steady toll on the insufficiently rugged tires on our trucks and takes it toll on our equipment as well. We lost a couple of motors to the heat and stress of drilling. The first week our new crews of local Touareg men have learned the routine and despite a few mishaps like getting a good rap on the head when a head wrap gets sucked into the fan, get the hang of drilling a good hole. This seems to be a welcome change for them in what looks to us like a very monotonous life of sitting in the shade while the kids herd the animals and the women cook and fetch water. We have injected a few highly prized consumer items into the local economy like stylish safety sunglasses and leather work gloves. Our mandatory ear plugs are far less popular so we must frequently remind our crew to wear them when the augers are running. The sunglasses are making the rounds among the locals, soldiers, and camp staff trading at ever higher prices. I get a visit every few days by those hopeful of getting a first or even second pair. We insist that our drillers wear their safety glasses at work so they can’t sell or trade them until the survey is over.

Entertainment is hard to come by out here and the wild navigation and driving habits of the security escort is a constant source of amusement. After a couple of weeks, they became pretty friendly and wandered into camp to see what they could mooch. Miles drove a hard bargain for a pair of his camo field pants. One of the soldiers wanted them bad enough to risk a court marshal and allowed the boys to have their pictures taken behind the gun on his technical. This was done in secret so the officers wouldn’t know. A climb to the highest point on the grid gave us a panoramic view of the area. Following an ancient tradition, the soldiers had carved ‘petrogliphs’ of their weapons into the rock at the top. Thanksgiving was pretty sparse but we made phone calls home with the sat phone. I was the only one who got a bird. The camp cook prepared a partridge that the soldiers caught and gave to me as a present. The boys had to settle for our usual dinner fare.

When the last of the radon detectors are in the ground we start to get a little barn sour, longing for home or at least a good meal, a cocktail, and a shower. Detector retrieval after they have been in the ground for 5-9 days means a visit to each point on the grid again. This goes pretty fast because we can follow our old tire tracks to each flagged point, haul the detector out of the ground by its wire harness, log it in to our field computers, and be off to the next in about 90 seconds.

Just another day in the
Sahara.

Wildlife is scarce in this part of the Sahara largely because the locals kill anything that moves. I was able to save one of the three snakes we encountered by catching it and letting it go a little ways from camp. The irony is the two killed by the Touareg were harmless and mine was venomous. We flushed a jackal one day and despite my protests, the soldiers chased it with their truck for ten minutes before it escaped into some rough terrain nearly exhausted. It looked like the jackal was trying to lure us away from a den. They performed the same disgraceful act with several fennec foxes over the course of the next few weeks. We discovered a nesting owl in a tree next to my tent and worried the adults would stop feeding the lone chick. We fed the chick a few bits of goat meat but it promptly puked them out. I felt the same way from time to time myself. We put a bounty of one piece of our supply of Halloween candy on mice in the hope that the village kids would be enterprising enough to feed the owl but the single reward claimed a day or two later was by the camp cook. By this time, the owl had climbed to the top of the tree, out of reach. At Stratamodel we take pride in our ability to fix any and all problems, so we fastened the mouse to a tent pole by the tail with some duct tape and enticed the chick to strike at it. Once we were convinced the chick was ready to eat, we dispatched the mouse with a coke bottle, loosened the tape and served him up. All of our worries about parental abandonment proved unjustified when we discovered one of the adults puking up a yummy pile of half digested rodents to the greedy chick a day later.

When the last detector came out of the ground we celebrated by eating lunch and drinking strong Touareg tea under a tree before heading back to camp to face packing. One of the men from the village brought a young female camel for us to ride but the saddle wasn’t tight enough and the camel was not completely saddle broken yet. This all made for a real spectacle with Touaregs hanging all over the camel trying to hold the saddle on and the camel frantically bellowing in protest. After we had our ‘rides’ we attempted to exhaust the remaining cans of beer in camp despite its fishy flavor from being refrigerated next to a bag of frozen fish.

Riding lessons. (big file takes a while to load)

We’re on are way to Niamey having run the gauntlet of bandit territory between In Gall and Abalak without a security escort. We’re never in personal danger but there is always the chance of a bandit roadblock where we could loose all of our vehicles, equipment and worse yet the survey data on our computers. The road to Niamey alternates between badly potholed pavement and rutted gravel for nearly 800 km and takes 12 hours to traverse. There are lots of interesting things to see along the way as we pass through a varied countryside of low sparsely wooded hills, open grassland, and small plots of farmland with a few withered millet stalks. The small villages are pretty sleepy except for the swarm of kids who appear out of nowhere whenever we stop. Donkeys, goats, sheep and cattle with huge horns drift back and forth across the road in front of us. The goats scamper out of the way when the driver first blows his horn. The sheep run but cluster more closely, never straying from the flock. The cattle keep crossing at their slow steady pace faithfully following the lead cow. The bulls, with their massive horns, plod along in the rear. The donkeys however, are indifferent to an approaching truck, no matter how much the driver blows his horn. They stand stupidly in the road as likely to stroll in front of us as to get out of the way. Some of the pedestrians exhibit a similar suicidal behavior so our drivers must be ready for the unexpected. Our driver values his horn above all other controls on the truck honking at everything from sparrows to camels. We want to get under the hood and snip the wire because it is driving us crazy.

Finally we arrive in Niamey where the air is thick with dust and wood smoke. The pristine air of the Sahara is now far behind us. Sunday evening traffic chokes the streets as we wind our way to our hotel eager for a long shower, a couple of G&Ts, a good meal, and our first sleep without the stars. Looks like we will finally get on that flight home in the early hours on Thursday and head back into the face of North American winter.

It is always a challenge to service our equipment and get it organized. This survey will be the latest iteration of our evolving gamma spectroscopy of shallow soil boreholes. I have been working closely with Paul Steinmeyer, a health physicist who creates portable spectrum analyzers. Together, we have successfully integrated gamma spectroscopy into our ArcPad based field data acquisition system. Stratamodel uses GPS enabled Trimble hand held computers for our sample logging. The addition of a gamma spectrometer linked by bluetooth to the Trimble units now enables us to record a spectrum at each of the hundreds or even thousands of points in one of our surveys.

Through the use of spectrometry, we can identify individual radioactive elements in the soil. Not only is this valuable for identifying potential uranium mineralization near surface but it enables us to evaluate the potential source of any radon based on the apparent support for radon generation in the soil. Radon anomalies with no parent radionuclides in the soil suggest radon transport from depth and a more deeply buried uranium source.

Our stop in Casablanca was interesting. We took a beat up old Mercedes taxi into town for a quick tour. Casablanca suffers from too many cars and not enough roads. Never the less it is still less congested than New York or Rome. The Grand Mosque is on a point that sticks out into the Atlantic. The Mosque looks fairly new and a few parts still seem to be under construction. The city is totally reconstructing its beachfront but there were still a few surfers out. A tour of Casablanca wouldn’t be complete without some shopping in the many leather stores. Scott couldn’t help himself so he bought a locally made leather coat to wear when riding his motorcycle. If this were a stop on the way home, we probably would have bought more. We tested the state of our digestive tracts by eating the local version of fish and chips. I might comment about how it all came out in the next blog.

We arrived in Niamey about 5 in the morning, just in time to watch Obama deliver his victory speech. Today, people in Niamey are celebrating.

Tomorrow we head 700 km north to In Gall where we will prepare to get Niger Uranium’s survey underway.

Lots more to do before we can get underway.  We have an air freight shipment with some of our equipment and supplies to send to Africa, visas to obtain, air tickets to buy, and a long list of items to include.  We’re a traveling hardware store and carry a small pharmacy not to mention electronics that now require 1,000 watts per night to charge for the next days work.

If all goes well, we should arrive in Niamey about November 1. Look for more posts from Niger in the coming weeks.

For those who have been here before, I hope you like the new style and our enhanced image, and video capability.  This should make our blog a little more entertaining. 

If you are using an older browser or Microsoft Internet Explorer, some of the features of this blog may not work correctly. If the thumbnails do not load, try hitting your browser’s refresh button. You may not be able to view the map or video. All other browsers should work well.

If you haven’t tried the new Google Chrome browser, now might be a great time to check it out. I’m pretty impressed with the enhanced image quality, fast page loading, and clean look. The only bug I have found is a problem using java driven drop down lists.

If only it were so easy as clicking the heels of our ruby slippers.  The trip home was certainly quicker by a day because our client chartered a plane to get us back down to Niamey.  After a day there, we got out in the middle of the night and had an uneventful trip back to New York.  We were too impatient to wait for the shuttle down to Dulles and the commuter back up to State College so we rented a car and drove home.

It’s still late Winter here which is something of a jolt to the senses when you are accustomed to 90 degree days, shorts and t-shirts, sitting around in the shade in the afternoon drinking beer….

Our survey is in sausage making mode.  The lab has the ingredients and we are ready to grind out maps and hopefully celebrate the identification of some hot anomalies to follow up on next month.

Meanwhile, I am headed to Toronto to the Prospectors and Developers Association of Canada annual meeting to learn what is new in the industry and line up more work.

That’s it for the current trip to Niger.  We will pick up the blog where we left off in about a month on our return trip.

We all hope that you have found the blog interesting and informative.  I certainly enjoyed writing it.  I have no way of knowing how many readers we have but judging from the statistics for my website it seems to have become fairly popular.  We are hoping for surveys in new countries this coming year even though we all really like Niger.  Stay tuned.

Cheers

Stratamodel

On a high lonely rock in the Sahara

We’re short timers now.  Homeland has chartered an aircraft to take us back to Niamey on Sunday so we can avoid the arduous two day drive.  All 1800 radon detectors have been retrieved from the
field and the films are safely packed in bags for their journey to the lab in Chicago for processing.  This recon survey has covered four thousand square kilometers, a sizable chunk of real estate by anyone’s standards.  The next step is to identify favorable areas and test them at a much greater sample density when we return in a month.

Our geologic traverses continue to reveal valuable information about the history of the basin that bears to one degree or another on our understanding of the origin of the uranium deposits.  Tony Kovschak, chief geologist of Homeland Uranium, has identified most of the specimens in our collection of fossil plants and animals.  The final phase of basin development (Cretaceous) was marked by a very large freshwater lake as evinced by a robust species of freshwater clam, algal mats, horsetails, and hungry hadrosaurs who grazed the edges.

Get off my back!

We still live in a happy camp.  Our grubby existence has developed into comfortable routine.  Up before dawn to a breakfast of Malrone (anti-malarial), bread, butter, and jam washed down with Nescafe for the unprepared or Italian roast for the more discerning palate.  The honey dippers are regular visitors until the sewer is completed.  Laundry is done by our security man with a bar of soap and bucket of tap water then hung out to dry on tent lines.

Everyone drinks from this contaminated well

We were treated to a Touareg roundup down at one of the regional wells yesterday.  After a morning geologic traverse, we pulled into their camp where a grand lunch lay waiting.  A ram was slaughtered and a platter of meat mixed with rice was placed before us on a rug under an acacia tree.  Strong green tea with as much sugar as tea was served in shot glasses.  The Hors d’houvre was aged sheep cheese. Armed with a soup spoon we all sat in a circle and dug into a mound of steaming food on a large platter.

Our lunch of ram and rice (probably made with well water).

After lunch we mounted our camels and under the watchful eye of the Touareg men were either led around or handed the rein.  Steering a camel is done with bare feet placed at the base of their neck.  Push the top foot and the critter goes right.  Push the bottom foot and he turns left or at least that is what I thought I understood from my teacher.  Pulling the rein, which is tethered to a ring through the camel’s right nostril, makes them complain in a loud Chewbacca growl.  I think the rein works like a brake and accelerator combination.  Mounting a camel takes some practice.  The camel kneels with all four legs tucked underneath but the saddle is still nearly four feet off the ground.  You mount by stepping on the camel’s left foreleg and throw your right leg over the saddle.  The pommel is a trident of carved wood or horn that is best grasped tightly when the camel rises.  They unfold their back legs pitching you forward at a 45 degree angle.  The front legs unfold next throwing you wildly backward.  Now, with your head eight or nine feet off the ground you have a grand view of your surroundings.  It’s a long way to the ground as Drew found out when he was pitched off as his camel rose.  Camels are just as ornery as some horses and like to rub you against the thorny branches of the nearest acacia.  They seem immune to the two inch needle sharp thorns, munching them like candy.  Their mouths are tough with a leathery pad instead of top front teeth.  Camels have large canine teeth on top that may only serve the purpose of inflicting a painful bite to a neighbor when they compete for water at the trough.  Their lips and nostrils are a wonder of evolution.  Like a seal or walrus, they can close their nostrils tight.  Their lips are as dexterous as the tip of an elephant’s trunk.

Looking like tourists in the Sahara.

After the men had a good laugh at our attempts to ride their camels, they showed us how it is really done.  The camp women gathered under a tree with a drum and began to chant, sing, clap hands, and beat a drum.  The men cantered their camels in a tight circle around the tree whooping.  We were squeezed into the center of the circle with racing camels passing just inches away.  After the show, a round of speeches was made pledging mutual cooperation and friendship.

This is how it is really done.

The regional well is in sorry shape.  Hundreds of animals are brought there daily for water.  The well is over 50 feet deep and the men and children labor to draw water and fill cement troughs so herds of sheep, goats, donkeys, cattle, and camels can drink.  Everyone in the village drinks from the same well.  All of these animals have left a rich layer of droppings around the well and the ropes used to lower the buckets slither through this muck with each hauling cycle contaminating the water in the well.  A government health agent was present and despaired of the situation and his inability through lack of resources to rectify it.  Homeland Uranium through their non-profit foundation has pledged to rebuild the well and create a system to alleviate the contamination problem.  A contractor will begin work within the next few weeks.

A model of how the well could be.

That’s all for now.  My next post will be from Niamey on the way home.  Be sure to check out more pictures here.

So long pard.

Ventifacts:  Rock eroded by wind borne sand. 

 Arlit, Niger Lat (DMS), 18° 43′ 57N, Long (DMS), 7° 22′ 5E,
Altitude (meters), 439.  Time zone (est), UTC+1 2008/02/09;23:20

“We gotta get out of this place, if its the last thing we ever do.”  A week of frustration and problems has been resolved by the addition of two of our old auger motors courtesy of our generous client Global Uranium of Toronto Canada.  Scott, Drew, and Miles worked to rebuild two more by cannibalizing parts from two severely damaged motors to make it all work flawlessly.  We got up and running again and put in our last 200 radon detectors which completes this phase of our survey.  We have now put in about 1800 radon detectors and will complete the survey in a couple more days when we have pulled all of them out of the ground.  Upon our return to the States next week, these will be sent to our lab for analysis.  My work will not be complete until I have processed the analytical results and interpreted the data in the context of what I have learned about the local geology.

Scott working his mechanical magic.

Every exploration program needs a capable manager.  Homeland’s exploration manager, Bill Cronk, is orchestrating a disciplined effort to collect and analyze as much data as possible to push the project to the next stage.  Drilling follow-up will be based on the compilation of geologic observations, previous drilling data, new geochemical data, and I hope our radon survey.  It is really exciting for us to be involved with such a hot prospect.

Bill and Akassa, the head geologist, discussing our traverse.

Life in camp has entered a new phase with the departure of half of the Stratamodel crew.  Miles and Tim are heading home to their own beds, western meals, loving friends and relatives, and all that other stuff we are missing daily.  We had a sendoff dinner/birthday party for Tim of grilled filet of beef on Thursday for all 20 of us here in camp cooked by Chef Tom.  Our regular camp chef has risen to the challenge and is making delicious meals raising camp moral to new highs.  Bill Cronk takes everyone in camp out to dinner at a local restaurant each Saturday night.  The infidels at camp (Bill and the Stratamodel crew) enjoy a glass of whiskey in the bar before dinner while the Muslims down Cokes and Fantas.

Drew, the master butcher dresses out Tim’s steak.

We are creating a camp crisis by showering regularly.  No not Stratamodel, the Africans!  My guys pride themselves on how utterly filthy they can get and remain that way for days on end.  Most of the Africans are far more fastidious and take regular showers.  This does have it consequences for camp however.  Our septic tank is small and has no drain field.  The honey dipper makes regular visits to pump the tank and haul off the residue to fertilize the gardens where we get salad that gives us diarrhea.  They really can’t keep up and twice this week Rabadinne our Touareg camp manager hired neighbor boys to dip out the septic tank by hand late at night so it would stop flooding the toilet and shower.  Crappy work to say the least and certainly even more miserable to do it between 11 pm and 2 am.  Bill has dropped big tips (by local standards) on these poor guys but what a mess in the morning with bad water spilled all over camp.

Rabadinne and the Honey Dippers (check out their latest CD on Amazon.com).

Mineral exploration is an adventure.  Nearly every day, Bill and I take a drive out into the desert to crack rocks with our hammers, examine the mineral grains, hash out our thoughts on their origin, and brainstorm how it might relate to the complex geologic history of this area.  We think we have identified the moment in time when the volcanoes just east of here flooded the basin with debris carrying a significant load of uranium.  We don’t work nearly as hard as our sampling crews and should be a bit embarrassed to complain of sore necks from bouncing around in the truck all day when our crews are busting butt digging holes and filling plastic bags full of dirt or drilling holes and dropping radon detectors in them 10 hrs a day.

This austere landscape yields a daily treasure of interesting geologic facts.  The barren terrain focuses us on the smallest things and what might otherwise go overlooked is gathered into our growing store of valuable geologic information.  Today we measured a field of petrified logs that was a kilometer wide by several kilometers long.  The logs where two to eight meters long and many of them where a meter in diameter.  Though most of these logs where replaced by quartz soon after they came to rest on the edge of an ancient lake, some parts of them adsorbed enough uranium to make our scintillometer sound like an Egyptian snake charmer’s flute as the gamma rays flood the detector.  The buzz of that scintillometer is to a uranium geologist what the glint of gold in a pan is to a gold prospector.

Bill wants to be buried like the ancients. 

Daily we see large mounds of rocks that mark tombs of Touareg.  The tombs seem to be everywhere and are a reminder that people have lived around here for a long time.  The effort to stack several hundred 10 kilo stones into piles 2 meters high amazes us.  Their stone grain grinders are scattered around the desert and speak of a time when this was a lush grassland where agriculture was possible and game must have been thick.  The last ostrich disappeared several decades ago but we still find broken egg shells where the chicks hatched out.  As you look at the pictures of the remaining grassland, keep in mind that these are the remnants of a much larger grassland ecosystem that has been desiccated and reduced to small areas where the Touareg people still hang on by tradition and a remarkable ability to extract resources from the poorest land imaginable.

We have made many friends here.  They readily overlook our foreign ways and I think appreciate our respect for their culture and religious practices.  Our French is improving daily and we are even picking up a few words of Tomacheck.  Just a little daily reminder that Americans are some of the World’s least educated people when it comes to foreign languages.  Most of our ‘uneducated’ crew speak at least three languages.  If we only understand English, can we really think we know what we are doing in foreign affairs?  Anyway, I can say that my crew of four young men are growing every day and they and I are sure we will never be the same after this experience.

The call to prayer comes at 4:30 am and it is LOUD.  All of us are so tired and used to the morning racket that we sleep through it.  Our African crews are up at 5:30 to eat.  Then at 6, they pray as a group in the ad hoc mosque they have created in a corner of the compound.  Our crews stop in the early afternoon for a brief prayer.  When they return from the field about 6 pm, there is another prayer.  At 7:30 a final prayer is conducted by one or two of the more devout with all of the rest in camp (except us infidels) praying in unison.  Unlike Christian prayer, which might seek forgiveness for sins or victory on the football field, Muslims simply bow in supplication and praise of God.  There is no appeal as an individual to a superior force, only submission and humility.

We are a contrast of high technology, grubby appearance, workplace hustle, haram practices, generosity, and religious indifference.  We are like jovial Martians that have landed among them and our antics are still mildly amusing and usually a bit puzzling.  We hope to get out of here before the novelty wears off.  But, before we do, we are leaving the latest Trimble hand held survey instruments and Africans who are trained to understand and use them.  These guys can truly say they are now among the elite around the world who use cutting edge technology in the collection of field data.

Mmm, the smell of grilled steak!

Let me begin with a short account of our survey progress and local news.  I will follow this with some observations and ideas about the local geology and the formation of our target uranium deposits.  When your eyes begin to glaze over reading about geochemistry and the evolution of this sedimentary basin, give it up and wait for the next blog and something a little less esoteric.

This survey is nearly done.  We are closing in on our goal of 2000 points even as our equipment is failing under the severe demands of the hard drilling.  The crew has been tearing the auger motors apart and cannibalizing parts to keep as many of the chain saw motors running as possible.  Despite this we are down to one working machine.  We will receive two replacements late Sunday which will boost us over the top early next week.  In about ten days we will have it wrapped up and head south to Niamey to catch our flight home about a week earlier than scheduled.

The security situation seems to have improved and the US embassy has relaxed some of its former travelers warnings.  We hope the convoy system has also been relaxed so that we might make better time back to the capital.  The areas we work are nearly deserted with the exception of a few scattered Touareg encampments were the crews have been trading plastic bags and a little money for bricks of sheep cheese and the occasional sip of camel milk.

Each day gets a little hotter and the morning chill dissipates a little earlier.  We will avoid the blistering days ahead this trip but when we return in late March, the heat will be on.  Still no signs of our February wind storms so we might be lucky enough to miss them. 

Every day brings in a new crop of interesting rocks and artifacts from the desert.  This area has been inhabited for tens of thousands of years and the debris left by generations is still out there for the taking.  One of the geologists brought in a bluish glassy mass shot full of gas cavities.  Small bits of copper where still stuck in the glass.  This slag could be several thousand years old and mark the site of an old furnace where people smelted malachite to produce copper tools.

 SOME THOUGHTS ON THE EVOLUTION OF THE TIM MERSOI BASIN

The rocks that keep arriving in camp tell a story of the evolution of this large inland sedimentary basin and are giving us clues to the development of the uranium deposits.  We know from past work that sometime in the middle Paleozoic, sediment began to accumulate in a shallow sea or large lake.  As the basin grew, sometime in the later Paleozoic, the land to the east began to rise even as the basin continued to subside.  If the first sediments to accumulate where marine, by the late Paleozoic or early Mesozoic, the basin was isolated from the sea and became an inland sea or large lake.

As the basin became even more isolated the surface and pore waters began to undergo their unusual chemical evolution.  This is evident from the gross chemical stratigraphy of the basin.   Sometime in the late Paleozoic, carbonate began to cement the sandstones and even more telling,  carbonate and perhaps gypsum nodules grew in the mudstones.  In isolation, this is not so unusual but the next chemical step, a signal event in this evolution, puts these early chemical steps in a different light and may be a valuable clue to the origin of the uranium deposits within the basin.  A rare mineral, analcime (a sodium rich feldspathoid), cements some of the sandstone, formed thin beds, and grew within the mudstones. 

Sedimentary analcime is currently forming in abundance in only a few places around the world in a specific type of physiographic, chemical, and geologic environment.  Our geologic understanding of the process of analcime formation dates from the late sixties and early seventies and is certainly not widely appreciated within the broader geologic community.  Sedimentary analcime forms at low temperature in the presence of very high concentrations of silica and sodium in water with a pH of 9-10 or higher.   Geologic conditions that match these criteria currently exist in some of the rift lakes of East Africa and playa lakes in volcanic terrains.  Climatic conditions and watershed geology are a key part of the analcime story.  Before speculating on the significance to uranium mineralization, a bit of geologic background must be explained.  Bear with me if you are a geologist.

Lake water with highly alkaline chemistry develops from a combination of relatively rare geologic and climatic events.  Climatic conditions can be summarized by the simple statement that evaporation must exceed rainfall.  This simple condition sets the stage for the development of a physiographic feature called a closed basin (a lake with inflow but no outlet).  Water entering a closed basin undergoes evaporative concentration which over time produces a brine.  Seawater, a familiar brine, contains sodium and chlorine.  Lake water in closed basins can evolve into far more complex and unusual brines that are determined by the chemistry of the rocks within the watershed, distance from the sea, and ratio of rainfall to evaporation.

Many such saline lakes exist in closed basins around the world.  For example, The Great Salt Lake in Utah, the Dead Sea in Jordon and Israel, and the Aral Sea in Central Asia are all closed basins.  Each of these three, while highly saline, does not have a particularly high pH.  Saline water contains the dissolved alkalies lithium, sodium, and potassium and the alkali earth elements calcium, magnesium, and barium.  These form positive ions (cations) that must be balanced by an equal charge equivalent of anions since water is electrically neutral (charge balance).  The typical anions in natural waters are chlorine, sulphate and carbonate and indeed these are the dominant anions in most saline lakes as well as seawater.  A garden variety brine would have elemental abundances Na>Ca>>Mg>>>K>>>>Ba>>>>>>Li and Cl>SO4>>>HCO3.  Chloride reaches most bodies of water through wind born chlorine from the ocean or the chemical weathering of chloride rich rocks.  Sulphate is derived from sulphide or sulphate minerals during the weathering of bedrock.

Rarely, a watershed has little sulphate and is far removed from the ocean so wind borne chloride is in short supply.  Since water must be charge balanced and chemical weathering continues in the watershed supplying a steady stream of cations to the water, the only other source of anions is carbon dioxide from the atmosphere itself. 

The bedrock in these somewhat unusual circumstances is frequently dominated by felsic volcanic or plutonic rocks (granite-rhyolite).  The paucity of a source of chloride and sulphate is complimented by a high ratio of alkali to alkali earth cations (K + Na / Ca + Mg) in these same types of rocks.

Closed basins are frequently structurally controlled.  Early stage continental rifting e.g. the Dead Sea and orogenic uplifting produce horst and graben structures e.g. the numerous playa lakes of Nevada.  These settings are predisposed to becoming closed basins under the right climatic conditions.   Broader closed basins can develop under the right climatic conditions in areas of crustal downwarping such as the Lake Eyre basin of south central Australia and Lake Chad of north central Africa.

The setting for the formation of sedimentary analcime is well established in the geologic literature and its presence in a basin can lead us to reach some general conclusions about the chemical evolution of the basin waters and give some clues to the likely tectonic setting.  In short, evaporation must exceed rainfall, a highly alkaline brine must evolve, and the basin must be dominated by felsic volcanic or plutonic rocks.  Moreover, these geologic conditions are often met in tectonically active areas undergoing crustal extension in an arid or semi-arid climate.

To return briefly to the Tim Mersoi basin, the gross chemical evolution can be read from the sedimentary cements and authigenic growth of minerals associated with brine evolution.  Early stage carbonate nodules and cement pass to the more exotic mineral analcime in the Jurassic and return to carbonates during the Cretaceous.

If your eyes are glazed from this discourse on brine evolution and geochemistry, how about a little volcanology to add some drama to this tale?

Imagine you are a lowly creature trying to scratch out a living beside a bad water lake and suddenly your day goes really bad.  About a hundred klicks east, a volcanic eruption sends a Plinian cloud 10,000 meters up into the atmosphere and it begins to rain ash and lapilli.  Some of you may remember the video of a horse in eastern Washington state shaking off a blanket of vitric ash from Mt St Helens when it erupted in the 80s.  Or, photos of the houses and cars covered with meters of vitric ash from Mt Pinatubo when it erupted in the Philippines a decade ago.  Our poor little creature scurries for the nearest bush but he is destined to end up like the citizens of Pompeii.

There is another piece of the puzzle that fits in nicely but does not necessarily prove anything with regard to the uranium mineralization.  By the middle Mesozoic, a critical event took place just east of the Tim Mersoi basin that may have introduced vast amounts of uranium into the local environment.   Volcanic eruptions of a somewhat unusual chemical composition began along a north south line about 100 km east of the basin margin.  Eight or nine volcanic complexes up to 70 km across are still preserved in the Air Massif to our east.  Their chemical composition is highly alkaline to peralkaline (high proportion of potassium and sodium relative to aluminum).  Volcanic rocks of this type from around the Earth are known to carry relatively high proportions of incompatible elements and metals (uranium, thorium, rare earth elements, tin, molybdenum, etc).  Incompatible elements are the dregs of magmatic evolution.  Loners who don’t readily form minerals of their own and misfits that aren’t easily incorporated into more common mineral structures because of their size, charge, or molecular orbital symmetry.

Repeated eruptions of vitric ash raining in the Tim Mersoi basin would have had a significant impact on the evolution of the brine.  At first, the very fine grained vitric ash is inert but with a little time it begins to dissolve.  As it dissolves it starts to release its load of silica, alkalies and even more important its payload of incompatible elements including uranium.  The rising load of cations sucks carbon dioxide out of the air to balance the charge jacking up the alkalinity.  Bear in mind we are not speaking of typical rhyolitic vitric ash but material derived from a highly alkaline and even peralkaline magma.  As more ash dissolves the pH begins to climb rapidly.  Additonal eruptions add vitric ash that starts to dissolve like alka seltzer in the steadily rising pH of the lake.  Zeolites and ultimately analcime begin to grow in the place of the dissolving ash.  The highly alkaline brine can not only dissolve ash and carry over 100 ppm silica, it can carry very high concentrations of uranium in solution as uranyl-carbonate complexes.

So now that we have uranium soup, where does it go?  The abundance of silicified sandstones, wood, bones, carbonate nodules and the like are evidence that silica dissolved in the brine, saturated and replaced every suitable host in its path.  Uranium having an enormous hydrated ionic radius is not so easily precipitated.  A suitable reductant is necessary to pop it back out of solution.  Buried organic debris like wood chips, logs, branches, humate cemented sandstones (Arlit) etc are just what is needed.

Here is where the trail grows cold and murky.  My tidy little geofantasy becomes far more speculative and as such less helpful in the discovery of a uranium deposit than I would like.  Never the less, lets blunder forward and see where it takes us.

Several observations about the structure, lithology, and timing of events are important.  The age of alkaline/peralkaline volcanism is Jurassic according to mapping done in the 60s and 70s.  The age of the sedimentary uranium hosts range from Carboniferous to Cretaceous.  The pre-volcanic uranium deposits discovered to date all lie along a large fault that has presumably been active since early in the basin’s history.  The mineralization occurs as clusters of humate cemented sandstone and sparse organic debris  in paleochannels.  The only(?) syn-volcanic deposit to date is the large blanket of sandstone directly overlying massive analcime beds at Imouraren.  Post-volcanic mineralization is known from limestones in the Cretaceous Irhazer formation and in sandstone at the Teguma-Irahazer contact.

How are these three types of deposits that span over a hundred million years of geologic time related?  At Imouraren, organic debris in stream channels overlying the pregnant brine was perfectly situated to adsorb uranium from the dewatering of the playa muds during compaction driven by sediment loading.  The mineralized Cretaceous sandstones and limestones of the Irhazer might have seen the remnants of this brine and they are not so separated in geologic time from Imouraren.

How to account for the Carboniferous deposits though?  I was an early skeptic of the local wisdom that these deposits are structurally controlled.  Now I am not so sure but still not convinced.  It may not be such a coincidence that Imouraren lies along the same structure as the deposits at Arlit (Arlit fault).  It is worth noting that the volcanic complexes to the east are aligned north-south, sub-parallel to the Arlit fault.  It is not hard to imagine movement along this fault during the volcanic events.  Fluid transport along this potentially transmissive structure could conceivably bring Jurassic age, alkaline, uranium bearing brine into contact with buried organic debris.  Indeed, the Carboniferous has analcime cemented sandstone beds and the zeolites clinoptilolite and huelandite have been identified in the mines thus evidence for alkaline brine is present in them as well.  I also can’t tell how well dated the volcanic complexes really are or how constrained the dates are so it is possible that volcanic events occured during the Carboniferous as well.

How is any of this helpful to the discovery of ore?  In the end what difference does an understanding of the process matter if it can’t provide the basis for concrete exploration strategies?  At the very least, if these observations and ideas have any validity at all, the practical implications for Imouraren and Arlit style mineralization are obvious. 

Identification of the main axis of post playa sedimentation where it directly overlies the massive altered tuff (analcime tuff) should be a high priority in any exploration program here.  In the field, there are well defined pebble and cobble trains of welded unaltered tuff eroded from the volcanic complexes.  Clear flow banding, fiame, broken crystals of sanidine, in an aphanitic groundmass make identification of the original emplacement of these tuffs from ash flows unmistakable.  Their distribution appears to be confined to linear trends where they comprise up to 90% of all cobbles present.  It is very likely that these are weathering out of former stream channels.  The coarse grain size (cobbles) speaks to significant stream power and the implication is that this represents a major axis of sedimentation.  The timing of the erosion of the welded tuff must be post eruption thus the air fall phase which yielded uranium to solution must lie at a lower stratigraphic horizon.  It is worth mentioning that the derivation of significant uranium to the system from the welded tuff at the site of eruption is highly unlikely.  These cobbles are unaltered, unweathered and highly impermeable.  They no doubt still carry their original charge of uranium.  It would certainly be interesting, though perhaps academic, to perform a chemical assay to assess the potency of the original magmatic source.

Arlit style mineralization remains more problematic.  If one accepts local wisdom, identification of favorable structures is key to their discovery.  Proximity to the main phase of playa development may or may not be important.  The relative size of these targets is also far less favorable than Imouraren type mineralization.  In the Arlit case, one is exploring for beads on a string where there are many strings without beads.  In the case of an Imouraren style target one must identify a flat lying blanket that covers many square kilometers if not more.