Kurt FriehaufPhotos from Igneous/Metamorphic Petrology

Kurt Friehauf

Petrology is the study of rocks (Petros = rock, ology = class that probably has a big lab component).
Igneous rocks form when molten (liquid) rock cools and crystallizes to a solid, like water freezing on a pond.  Sometimes that happens on the surface of the earth, as in the case of lava flows and other volcanic eruptions.  Sometimes that happens deep underground, requiring hudreds of thousands to millions of years for the magma to solidify. 
Metamorphic rocks form when heat and/or pressure cause rocks to recrystallize and change.  Remember Franz Kafka's Metamorphosis (about the fellow who wakes up one morning to find himself transformed into a giant bug), or how caterpillers form cacoons and transform into butterflies?  Well, so it is with rocks!
My petrology course focuses on the major processes in forming igneous and metamorphic rocks.  We have several fieldtrips in the class, including a 5-day long camping trip in the Adirondack mountains of New York where there are some spectacular rocks!!!

Adirondacks 2004
Adirondacks 2004Adirondacks Autumn 2004 - we started at the Barton garnet deposit

Adirondacks 2004Panning for garnet gems.  The Barton family are truly excellent citizens!  They are a credit to mining and the Adirondack region.  They do a lot of work with school groups, run a tight and clean ship, and produce great product.  Great people!

Adirondacks 2004Adirondacks 2004Garnet porphyroblasts with hornblende rims in metamorphosed metaolivine gabbro.

Adirondacks 2004Zach posing for scale with garnets

Adirondacks 2004Adirondacks 2004Wollastonite is used in a variety of everyday products, including a sort of microscopic re-bar in plastics!  How massive deposits of wollastonite form is the puzzle students must solve here!

Adirondacks 2004Adirondacks 2004Josh showing good hand lens technique.  Head held high to allow more light - lens just at eyelash distance from his eye - eye that's not looking through the loop is open and relaxed - no facial scrunching.  Good job!

Adirondacks 2004Adirondacks 2004Andy was such a professional and a great guy.  It's both very happy and quite sad for professors when good students graduate.  I miss a lot of them.

Adirondacks 2004We camp at night to keep costs down.  It's tricky finding campgrounds that are open after Labor Day, but we seem to manage.

Adirondacks 2004Adirondacks 2004I used to run this fieldtrip in the late spring, but the snow caused some problems.  Moving it to fall creates different problems, but was overall a good idea.

Adirondacks 2004http://faculty.kutztown.edu/friehauf/classphotos/petrology_adirondacks_DSC00942.jpgCharyn always cooked up something wonderfully aromatic and different.  I'm afraid I usually just throw together spaghetti, burritos, or other very quick and simple food when I cook for the group.  This year will be different, though!  I have big plans!

Adirondacks 2004Adirondacks 2004Anorthosite - a special igneous rock characteristic of the Adirondacks - warrants close inspection.  These students are not kissing the rock, rather they're looking at the mineral crystals with high powered magnifying lenses identical the the jewlers loops you might have seen in diamond store. 

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Adirondacks 2004Adirondacks 2004http://faculty.kutztown.edu/friehauf/classphotos/petrology_adirondacks_DSC00951.jpgIt's always good to see thoughtful discussion on the outcrop.  Here, students discuss the different types of anorthosite found in the outcrop and the relative timing of the injection of different magmas.

Adirondacks 2004Adirondacks 2004For me, this will always be the Outcrop of Tears.  The first group I took up here didn't like this outcrop at all because I asked them to precisely estimate the proportions of different minerals in the igneous rock.  It was a fiasco!  Since then, I've taken two other groups and no one's had problems doing it. 

Adirondacks 2004Adirondacks 2004Look ma!  No tears!  This group did a great job on this outcrop!

Adirondacks 2004In addition to getting right up to the rock, it's also important to step back and try to see the big picture.  That's a lesson I learned from one of the smartest guys I've ever met (Lans Taylor - extraordinarily nice guy and so smart it was spooky!). 

Adirondacks 2004Adirondacks 2004Zach and Josh trying to work out the rock type.  The debate here was in the identity of the dark colored mineral - biotite, hornblende, pyroxene, or olivine?  The Adirondacks have some unusual rocks, so it's a good question!

Adirondacks 2004Adirondacks 2004I guess I must have interupted them in their work to warrant scowls like this!  It's good to see people so focused on their work!

Adirondacks 2004Adirondacks 2004The Lion Mountain iron deposit was mined long, long ago, but is now closed.  It's a good example, though, of granitic gneiss hosted iron ores of the Adirondacks.

Adirondacks 2004Adirondacks 2004After studying the iron ores in the pit, we stop to visit the giant pile of sand made from ground up ore.  It's an amazing pile!!

Adirondacks 2004Adirondacks 2004Three students climbed to the top to illustrate how big this pile of sand really is. 

Adirondacks 2004http://faculty.kutztown.edu/friehauf/classphotos/petrology_adirondacks_DSC00980.jpgPatroling campsite for litter - leave the site cleaner than you find it!

Adirondacks 2004The fayalite granite is a neat stop.  Fayalite is a mineral belonging to the olivine mineral family.  Olivine is typical of very iron-magnesium rich rocks more characteristic of the ocean floors.  Granite, on the other hand, is iron and magnesium-poor and so only very, very, very rarely contains olivine.  There are some chemical reasons for this, but I can't tell you on this website or else my students will know the answer before they get to the outcrop.  One big part of fieldtrips with me is learning to make careful observations.  The other big part of fieldtrips with me, though, is thinking about rocks in terms of process while you're on the outcrop. 

Adirondacks 2004Adirondacks 2004This outcrop is half red and half gray.  What causes this difference?

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Adirondacks 2004Lunchtime!

Adirondacks 2004Mylonite is a layered rock that forms by crushing of the mineral grains when the rock is sheared.  The two main zones of the Adirondack region are separated by a mylonite zone, suggesting one of the zones slid down along a shear zone from a different place. 

Adirondacks 2004Andy points out the direction of the lineation in the mylonite. 

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Adirondacks 2004Proud of their oriented sample, Josh and Andy pose by their treasure.  An oriented sample is one which the geologist carefully records the orientation of before bagging.  This allows the geologist to orient the sample in the exact same direction, tilt, etc. back in the lab.  Some mineral textures tell us the direction a rock was smeared/squished/etc.  We need to be able to analyze those mineral textures knowing their orientation!

Adirondacks 2004Adirondacks 2004Cooling off in Cranberry Lake after a day of rock study.  The temperature was actually quite cool, but a dip in a mountain lake is tough to pass up! 

Adirondacks 2004http://faculty.kutztown.edu/friehauf/classphotos/small_petrology_adirondacks_DSC01008.jpgAdirondacks 2004It's good to wake up early so you can see the sun rise.

Adirondacks 2004Adirondacks 2004The world is an incredibly beautiful place, isn't it?

Adirondacks 2004Migmatite is a rock that forms when rocks are buried so deeply and heated so much that they start to melt.  The liquid migrates into swirly zones like the ones Dana's modeling here. 

Adirondacks 2004A basalt dike cuts across a meionitic marble in the northwest Adirondacks.  Rocks in the northwest Adirondack lowlands are mostly metamorphosed sedimentary rocks.  The basalt formed much, much later when molten magma injected into fractures.  Such basalt dikes are commonly associated with rifting, although I don't know if this particular dike formed during the Neoproterozoic rifting, or the late Triassic rifting event.

Adirondacks 2004Adirondacks 2004The Train Wreck - a very famous outcrop in the Adirondack region.  The dark blocks of garnet were once a cotinuous, albeit brittle bed of rock.  The surrounding gray swirly stuff is marble.  In metamorphic temperatures and pressures, the marble flows like toothpaste, but the brittle garnet fractures into pieces, which are smeared out to to geologic forces.

Adirondacks 2004Glacial striations formed when the giant continental glacier of the last ice age scraped across these rocks 20,000 years ago.  The scratches tell the direction the ice was flowing.

Adirondacks 2004The Steer's Head outcrop - studing chemical reaction rims that form when rocks of different compositions are in contact with one another during metamorphism.  Students here must first identify the minerals present and then deduce what chemical reactions took place.  Again, I can't tell you the answer right here in case future students are reading this!

Adirondacks 2004Adirondacks 2004Close-ups of the reaction rims

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Adirondacks 2004Talking about the Balmat zinc deposit with Bill DeLorraine - a geologist working at the mine.  Bill's incredibly sharp - the folks at HudBay Minerals, Inc. are lucky to have such a smart and experienced guy working for them.  Here, the class poses by the three dimensional mine model that shows the ways the orebodies twist and turn deep underground.  We were not able to tour underground, though, because the mine was closed down.  The Balmat mine, being a smaller mine, must open and close depending on the price of zinc metal.  Opening and closing a mine's opperations is an expensive endeavor, so it's not a decision made lightly.  They keep the mine pumped dry, though, during the time they're closed down, which dramatically reduces the start up costs.

Adirondacks 2004Adirondacks 2004Hunting for marble outcrops in the Adirondack jungle.

Adirondacks 2004Adirondacks 2004Some strange features in the marble.  The locations of these features is a secret - they are pretty incredible and should not be disturbed, as you well know if you recognize what they are!


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