Photos from Geology Club field trip to Yellowstone and southern Montana mines - May 2009

Kurt Friehauf

YellowstoneThe Geology Club traveled to Wyoming and Montana to see Yellowstone volcano and tour mines in southern Montana. 
We started at Yellowstone.  Early May is a cold time to visit the park and we found that some of the main roads were still closed.  We didn't mind a little snow and cool air, though!

Yellowstone - Mammoth Hot SpringsIt was a beautiful day to visit Mammoth Hot Springs!  The white on the mountains in the background is snow, but the white, steaming flat behind us is covered with travertine deposits. 

YellowstoneThermophilic bacteria thrive in the hot waters at Mammoth Hot Springs.  There was a fascinating variety of types of colonies.

YellowstoneThe wildlife at Yellowstone is, of course, one of the great attractions. 

YellowstoneBison are one of the most undulates in the park.  We steered clear of them!

YellowstoneThere weren't many bears roaming around this early in the season.  We steered clear of the bears, too!

The group with YellowstoneYellowstone Falls in the background.  It was drizzling a cold rain, so everyone's bundled up.

YellowstoneYellowstone Falls with plenty of snow and ice

YellowstoneThere are places where hot springs flow into rivers. 
Hot plus cold = warm!

YellowstoneIt was snowing at the time, but the hot springs were toasty warm as long as one stayed submerged.  Getting out and dressed again was a different matter! 

YellowstoneRoaring Mountain steams with heated groundwater and sulfurous volcanic gases. 

YellowstoneOld Faithful geyser - where superheated groundwater boils to steam that pushes water up over a hundred feet into the air.

YellowstoneThere are several geyser fields at Yellowstone, each with its own special features.

YellowstoneGrand Prismatic Spring is made colorful by different types of bacteria growing in the water. 

YellowstoneThis geyser melted a circular hole in the snow.  Yellowstone is truly a places of contrasting opposites!

MontanaThe historic geothermal field extends beyond the limits of the national park.  After leaving Yellowstone National Park, we explored some of the travertine deposits that had been mined for counter tops and decorative stone. 

YellowstoneThe travertine was mined with wire saws to cut the rock into slabs.  The remaining outcrop reveals the internal layered structure of the travertine wonderfully!

MontanaThis hilly landscape is what geologists call hummocky terrain.  Hummocky terrain like this can form either from landslides or as glacial deposits.

MontanaThis basalt flow contracted during cooling, causing the new rock to fracture in a characteristic pattern called columnar jointing

MontanaThe fractures form 120º triple junctions, resulting in pillas with hexagonal cross sections.  Rainwater seeps between the columns along the fractures, chemically altering the rock along the outside edges of the blocks. 

MontanaWhen magma injects into fractures in the rock, the magma cools to form a tabular rock body called a dike.  When magma injects between sedimentary rock layers, the tabular igneous rock body is called a sill.  The igneous rock pictured here was more resistant to weathering and so sticks out as a striking ridge. 

MontanaHere is another example of an igneous dike exposed by differential weathering of the softer surrounding rock. 

MontanaEmigrant Gulch was a historic gold mining district.  The gold occurred in stream gravels - what economic geologists call placer deposits.  When gold is mined from placer deposits, the gravel waste piles are called dredge tailings or dredge spoils.  Dredge spoils are a great way to see the wide variety of rocks that occur upstream.  We spent several hours exploring these tailings. 

MontanaMontana is beautiful!

MontanaA very smart geologists explains contact relations for the J-M Platinum Reef outcrop near the Stillwater Mine.  The Stillwater Mine produces platinum, which is the essential ingredient in pollution-reduction automotive technologies, as well as food processing plants that reduce polyunsaturated fats in our diets.  There are only a few platinum deposits in the world.  The Stillwater is the only platinum deposit in the United States!  The Stillwater Mining Company is the only thing keeping us from total dependence on other countries for platinum and related metals.  (South Africa and Russia are the primary producers of platinum in the world).

MontanaJ-M Platinum Reef in outcrop at the Stillwater Intrusive Complex.  White = plagioclase, dark = pyroxene. 

Montana crystalsCoarse-grained, white plagioclase engulfed smaller green pyroxene at the Stillwater Intrusive Complex. 

MontanaHarley stands by some of the inch-scale layered igneous rock.  The layers were originally horizontal, but were tilted during uplift of the mountain range.  Layering like this is unusual in plutonic igneous rocks that form deep within the Earth, except at the Stillwater Intrusive Complex where layering is the norm.

MontanaMagmatic platinum sulfide grain (circled) near large (palm-sized) pyroxenes in a pegmatitic portion of the J-M Reef in the Stillwater Intrusive Complex.

MontanaOphitic igneous texture in which a large, dark crystal of pyroxene grew around many smaller crystals of white plagioclase.  That's my finger for scale at the bottom of the photo.  Great igneous rock textures like this abound in the Stillwater Intrusive Complex. 

MontanaThe Kutztown University Geology Club after touring the Stillwater platinum mine.  The white circles painted on the rock in the background are places where magmatic sulfides are clearly visible, indicating this was a particularly high grade part of the orebody. 

MontanaHistoric Butte mining district viewed from the visitor's overlook.  The headframes in the foreground were the entrances by which the old timers accessed the underground mine workings. As you can see, environmental reclamation after mining was not a concern in the olden days.  There's a new miner in town these days, though - one that is doing its best to clean up the mess:  Montana Resources.  I was very impressed by their environmental efforts!

MontanaThe Berkley Pit - a giant vat of acidic, metal-contaminated water that formed when mining ceased in 1982 and groundwaters began filling the old mine pit. 

Montana Resources has figured out a nifty way to help clean this mess up!  By pumping water out o fthe pit and running it over old scap iron, the toxic copper deposits, while the scrap iron dissolves.  The iron-bearing water is released back into the pit so it does not harm wildlife.  The copper is sold to pay for the pumping (plus a very small profit to sweeten the deal for Montana Resources). 

The Continental Pit can be seen in the background. 

MontanaStudying vein types in the Continental pit.  The copper deposit in the Continental pit consists of many tiny veins or quartz, pyrite, and other sulfur-bearing minerals such as chalcopyite and molybdenite.  By carefully studying which veins cut and offset others, we can work out the sequence of events that formed the orebody. 

MontanaAn example of a thick quartz-molybdenite vein in the Continental pit. Molybdenite is the silver colored mineral forming bands in the vein. 

MontanaThe group poses in an electric shovel that was unplugged for maintenance. 

MontanaA working shovel in the Continental pit loads a haul truck with ore to be transported to the crushers before concentration.

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