Time flies and research inches along but graduation only creeps closer.

I freely admit it...I have totally neglected the blog over the past academic year.  My excuse would be that "things have been crazy, unsettled, and really hectic around here," but the longer I am in graduate school the more I realize that anyone in academia probably claims the same excuse.

In the same format as several of my most recent posts, here is a partial summary of highlights from the past two semesters in no particular order:

• This month I become my adviser's most senior graduate student.  The labmate ahead of me defends her dissertation at the end of June and will be headed off to new science adventures. That puts my adviser back to three graduate students for this coming year.
• I applied for and was granted a Graduate Research Grant from the Geological Society of America to work on a comparative study of detrital garnet ages versus detrital zircon and monazite ages from modern sediments in the southern Appalachian mountains.  This study will be either the second or third chapter of my dissertation!  In addition, I was recognized as one of 10 (out of 774 total applicants) awarded an Outstanding Mention for exceptional merit in conception and presentation of my grant application.  There's a chance that I may be attending the GSA fall meeting in Vancouver.
• I completed two more classes.  I finally got to take a tectonics seminar and an isotope geochemistry course.  It's about time for an official isotopes course since I call myself an isotope geochemist..don't you think?!  Only two more courses to go during the remainder of my PhD.
• I am currently writing my first, first-author paper, which will also be the first completed chapter of my dissertation.  I presented part of the research that the paper is based on at the AGU fall meeting in San Francisco last December.
• During April and May I worked on a collaborative research project with Drs. Lenka and David Baratoux.  They came to Boston University as visiting scientists to date garnet from West African rocks as a part of the WAXI program (West African Exploration Initiative).  It is pretty exciting to be working on rocks that are being studied for the very first time!  I have been involved as an adviser for experiment planning, as a lab assistant as they learned the techniques for garnet geochronology here at BU, and as the lab tech for completing the clean-up work now that they have returned home.

The coming months should include work on preliminary data for a new grant application, completion of my first-author paper on garnet from the Jack Hills, and lots and lots of sample preparation for upcoming projects.  I'm also hoping to write a step-by-step methodology as I work in the lab this summer.  The plan is to include portions of that guide as blog posts illustrating what a day in the life of an isotope geochemist looks like.

In other news, I have been working on a brand new personal, academic website.  You can now find my personal page at www.kathryneccles.com.  Right now it is fairly basic and includes my professional background and current work, but soon I hope to add lab pictures, lesson plans, and more. I'm always open to suggestions for website improvements as I move towards graduation and job hunting in the next few years!

I'm a 3rd year?!

Now that the brand new crop of first year graduate students are starting to arrive, I will officially have to introduce myself as a third year PhD candidate.  I remember meeting one of the third year students when I first started grad. school and thinking "Wow!  She has it all together and knows what she's doing!"  Now I am supposed to be the third year student who has it all together...and some days it certainly doesn't seem like that'll ever be true!

Also, two of the brand new students are joining my adviser's lab group- which means I am no longer the "baby" of my adviser's students.  I am moving up to "middle child" status and looking forward to it.  :-)

As I think ahead to the coming year (or even more immediately to fall semester), there are potentially some big research goals ahead!

• Present research at AGU.  I am going to the AGU conference in San Francisco, CA in December for the first time.  I am very excited that I will finally be able to share my most recent research, present some cool old garnet ages, and see lots of science.  (Plus it's my first visit to San Francisco and I'll get to meet up with an old friend or two!)
• Write and submit for publication my first, first-author paper.  It's time to tackle my first paper!  It's going to cover the same research being presented at AGU.  Then I will finally be able to openly share what I have been working on for the past year.
• Lots and lots of lab work.  I think it's pretty self-explanatory- I need to generate as many quality garnet ages as possible on rocks from around the globe.
• Hopefully some field work!  Who doesn't want to go look at some of Earth's oldest rocks in northern Canada or Greenland?!
• At least two more classes.  I finally get to take isotope geochemistry.  About time, since I'm an isotope geochemist!

Here's to another year of graduate school adventures and LOTS of science ahead!

(Bonus update: This week I officially hit my 300th sample run on the TIMS.  Time for a new log book!  I also made the mistake of calculating how much time that means I've spent sitting in the TIMS chair and running the instrument and came up with a rough estimate of more than a month's worth of 12 hour days.)

Hitting the Highlights

I can't believe that it has been about nine months since I wrote a blog post.  Blogging has unfortunately had a tendency to get pushed further and further down the to-do list in favor of new data or pressing deadlines.  

Let me just hit the highlights from the past nine months.  Since the last post I...

• Applied for and was awarded an NSF Graduate Research Fellowship that will cover my stipend for the next three years of my PhD.
• Submitted my dissertation proposal plus took (and passed) my written and oral qualifying exams so I am now officially a PhD candidate.
• Completed a couple more classes.
• Dated detrital garnets from two new field sites.
• Attempted to still sleep, eat, and not let science totally consume my life.
• Spent the entire past 6 weeks working super long days and cranking out data for an AGU abstract and my first paper.

Hopefully the next nine months will hold equally exciting highlights and more consistent blog posts!

TIMS Tutorial: The Basics

Monday morning I finished the first drafts of all three of my NSF graduate research fellowship application essays.  Monday afternoon\Tuesday morning I finished this week's homework set for the applied statistics course I'm taking.  But now it's Wednesday afternoon and today I feel like I haven't completed anything besides discovering new research roadblocks.  It seems like graduate school is full of bursts of fairly impressive productivity followed by lulls where the instrument doesn't work, experiments fail one after another, and the to-do list gets longer and longer but nothing gets marked off.  If anyone with vastly more science experience has tips for how to overcome lulls I'd be happy to listen!

In an attempt to do something productive and work on my science communication skills (I need all the practice I can get...qualifying/comprehensive exams are looming!) I have decided that one of the projects I'm finally going to tackle during my lab work lull is to write about the main instrument that I use in my research.  Plus, I often learn best by teaching!  I've been meaning to do this for a while and if you've seen references in my posts to "the instrument" or "the TIMS" and wondered what on Earth that was..this is the series for you!  Hopefully, today's post will provide necessary background for those of you with little or no exposure to isotope geochemistry.  Next post I'll show you how the samples get loaded onto the machine and eventually we'll talk about how the machine actually goes from the samples to a useful result and what running the TIMS is really like.

The primary instrument we use in my research lab is a "thermal ionization mass spectrometer," which we refer to as "the TIMS" for short.  [Which, incidentally, has lead to several comical instances where people overheard me telling someone that I "date garnet" or "spend a lot of time with the TIMS" and then inquired about the romance in my life after assuming I was talking about a boy! lol] Breaking down the full name of the instrument actually gives a pretty solid overview of the instrument's purpose.  The TIMS uses high temperatures to ionize (break down into individual charged atoms) the sample, separates the ions by mass using an electromagnet, and allows us to measure the relative abundance of ions at specific masses to determine isotope ratios.  If that just went over your head, don't despair yet!  I promise upcoming posts will have pictures and likely use household objects as analogies to break this overview down into manageable parts.

First...a little general background on geochronology and why I use this crazy instrument.  As an 'isotope geochemist,' my goal is to figure out the age of each of my garnet grains and then use those ages to examine bigger questions about how mountains form and the surface of the Earth changes.  Figuring out the age of the garnet is possible because garnet includes trace amounts of a radioactive element called samarium (Sm) that decays to the element neodymium (Nd) at a known rate.  It takes 1.06x10^11 (106 billion) years for enough Sm to decay so that only half of the original amount is left (called the half-life).  Also, garnet is basically never 100% pure...it usually contains little bits of other minerals that we refer to as inclusions.  To borrow an example from my adviser...you can think of it as a chocolate chip cookie.  The cookie is the garnet and the chocolate chips are the bits of other minerals, or inclusions, inside the garnet.  Many of these inclusions contain a different ratio of  Sm to Nd than the pure garnet (just like the chocolate chips and the cookie base would have different ratios of sugar to milk).  Therefore, I use the TIMS to measure the Sm and Nd ratios in the pure garnet and in the inclusions.  Since the ratios are different and the rate of decay is known, when I plot the ratios for the pure garnet and the inclusions I can define a line between two points, called an isochron.

The slope of the isochron = The age of the garnet!

By the time I am ready to walk into the TIMS lab and start an analysis, I have already been working through sample preparation and clean lab chemistry on a single garnet grain for several weeks.  Those week of work result in a set of 4 beakers, each containing a single bead of dried goop about the size of a ballpoint pen's tip.  The four beakers contain the Nd from the pure garnet, the Sm from the pure garnet, the Nd from the inclusions, and the Sm from the inclusions.  Each isochron that results in an accurate age requires all four samples to run successfully on the TIMS, usually with only one shot at getting each one right. 

This is a very simplistic overview of geochronology and mass spectrometry, especially since there are entire courses on the principles of these areas of study.  Basically, once you understand that by measuring isotope ratios of Sm and Nd we can figure out the age of garnet, you understand the purpose of using a TIMS and one of my basic research goals. The remainder of my research examines ways that we can apply these methods to new materials that have never been dated or how the ages that I get tell us about the rates of metamorphism, when sedimentary basins open and close, how metamorphic conditions change over time, and much more.  

My First Garnet Age

It's been way too long since I've written a post.  I've saved up a nice long list of topics that I can write about and adventures from the last month and half but just haven't gotten around to writing the posts yet.  I'm hoping that this post will be the first of several over the next couple of days to get more or less caught up and whittle down my idea list.  Instead of going chronologically, I'm going to start with a science update...since that's the cause of my delay in writing anyway. :-)

There has been a lot of exciting science in the past month and a half since I wrote about my first trip to WHOI to use the SEM.  I'm balancing two classes (Geodynamics as well as "Thermodynamics and Kinetics of Tectonometamorphic Processes," which is taught by my adviser) and finally getting pretty close to being independent on most of my research procedures after learning several new steps these past couple of weeks.

The biggest push for research has come over the past two weeks.  This past summer when I did fieldwork in Scotland (see earlier posts if you missed the beautiful Scotland scenery!) I collected several samples and shipped them back here.  In November I sent two of those samples off for crushing and mineral separation and they came back roughly three weeks ago.  As I was in a meeting with my adviser just over two weeks ago, we were talking about research priorities and he mentioned that he would love to have an age for garnet from one of the samples ahead of his upcoming talk at the University of St. Andrews, Scotland on his European speaking tour but he wasn't sure if it was possible.  Normally taking garnet from raw mineral to an age takes us three to four weeks, with two weeks being the absolute fastest speed possible if everything goes according to plan.  I agreed to try and plotted out every step on a calendar, knowing that I would make it with just about 12 hours to spare if I succeeded.  It was also complicated by the fact that I have never completed some of the final steps, because I just hadn't gotten there yet with test samples.

So, basically the last two weeks were two solid weeks of lab work.  It included a second trip to Woods Hole to do SEM work on the Scotland samples (and incidentally learning how to change an SEM filament...), about a week and a half of 12+ hour workdays in the clean lab in my superhero get-up, two days of learning to load samples and how to load the mass spec., and two days of learning how to run our instrument.  (Eventually I'm hoping to write a series of posts to show you some of the basic methods and our instrument, the TIMS.)  Amazingly, my sample survived and I can finally say I have my first garnet age!!  Not only was this the first time I generated an age by doing the procedures from beginning to end, I made it within two weeks (with 11.5 hours to spare), it was a ridiculously small sample (I started with only 4mg of garnet...4 sand grains basically), many of the procedures I was doing independently for the first time or I was learning with supervision for the first time, and the result was right in the expected ballpark!  If you can't tell, I have been quite pleased for the last day or two.

Now that I have my first age under my belt, I can start testing and implementing some of my ideas for changes to the procedure to improve how our lab works with very tiny samples and for further method development on the new garnet dating system I am developing.  While I'm excited about my first data point, there are many improvements to be made and many more points to be gathered.  Onward in the pursuit of science.

Grains under the Microscope: A WHOI Adventure

About a week and a half ago I had the opportunity to visit Woods Hole Oceanographic Institute (WHOI) on the southern part of Cape Cod in Massachusetts.  I took a day trip away from my usual research at BU in order to gather some test chemical data on a couple of my detrital garnet samples.  I received an invitation from a research scientist at WHOI offering me the opportunity to try out a piece of equipment we do not have in our department at BU.

Before I describe what my day at WHOI looked like, let me give you some general background on the goal of the trip and the method that I was using for those of you who are unfamiliar with the SEM.  I traveled to WHOI to use a tabletop scanning electron microscope (SEM).  A scanning electron microscope uses a beam of electrons that bombard the sample.  When the electrons collide with the material being analyzed, different types of detectors can be used to provide information about the electrons that are scattered or energy that is emitted to learn more about the sample being analyzed.  The instrument I was using is smaller than most standard SEMs and is designed to be user-friendly, to take up less space, and to allow for analysis not just of polished, coated samples (which is the standard procedure) but also of rough, uncoated samples using a lower vacuum setting.  This makes this instrument an excellent candidate for analysis of my samples, since the grains do not have to be coated or polished, which would destroy them.  The tabletop SEM is equipped with two different detectors- a BSE detector and an EDS detector.  BSE stands for backscattered electrons and measures the electrons from the beam that are scattered and reflected by the object being analyzed.  It allows for the differentiation between heavy elements and light elements, since heavy elements scatter electrons more strongly.  From this differentiation, an image of the material being analyzed is generated using grey scale that can show surface detail or different mineral phases.  Below is an example from one of the grains that I analyzed at WHOI, though this particular grain is zircon rather than my usual garnet subject.

BSE image showing a zircon grain, analyzed at WHOI 1/20/2012

Besides BSE, the SEM can also do EDS analysis, which stands for energy-dispersive X-ray spectroscopy.  The electron beam hitting the sample can trigger the release of x-rays and the energy of the x-rays released is characteristic of the major elements that compose the object being analyzed.  This makes EDS useful for preliminary chemical characterization and mineral identification.  EDS results in a spectrum showing major element peaks and can also generate atomic and weight percentages for major elements using spot analysis.  Basically, we can get a general idea of the composition of the material being analyzed.

While I was at WHOI, I analyzed twelve different detrital garnet grains.  I used grains from two different locations in Vermont that we have been using as test samples throughout the method development process.  Three of the grains were from one location and the other nine were from a second location.  The sand collected at the second location contains detrital garnet of different colors, so I was able to analyze three grains of each color (red, orange, and pink) hoping to test the ability of the instrument to differentiate between garnet with different compositions.  When doing detrital work, it is important to be able to identify populations of similar grains that likely originated from the same general area and should be roughly the same age, since a single detrital sediment can contain different populations of garnet grains that originated from different locations and were affected by different conditions.  In addition to the garnet analyses, I also analyzed many grains of any other mineral that could remotely resemble garnet under the microscope from one of my other field areas to verify that garnet is not present in the sample.  Here is a picture showing how the grains were mounted for analysis.  The grains are still attached to this mount- they are just too small to see easily in the picture and blend into the carbon sticky tape.  The grain mount is sitting in a small weigh boat to minimize contamination.

Grain mount for SEM using carbon sticky tape

Just for fun, let me give you a look at what my day of research looked like.  My commute to WHOI started around 6:30am and involved two different subway lines, a Peter Pan bus, getting picked up at the bus station and a short drive to WHOI's Quissett campus.  I arrived around 10:00am and started learning how to run the instrument and by 11:00am I was running the instrument independently.  I then spent the next five to six hours (minus a lunch break) analyzing as many grains as possible and accumulating roughly 90 computer files between BSE images, EDS analyses, etc.  Then I took a shuttle bus to Woods Hole, where I ate dinner in an awesome little cafe while waiting for my bus to Boston.  (If you ever find yourself in Woods Hole, MA..I highly recommend eating at Pie in the Sky. It was delicious!)  After a bus ride and two more subways, I arrived home around 10:30pm.  It was a long and tiring day...but definitely worth it.

Here is one final picture, showing me running the SEM at WHOI.  Not only did I learn a new instrument and gather helpful information on some of my samples, I am learning how to be an independent scientist!

Me running the tapletop SEM at WHOI

Away from Boston and Back Again: Christmas Break and a Research Update

Two weeks away from Boston for Christmas break, a week and a half back in Boston working on research without the distraction of classes, and the start of classes impending in the coming week.  It's been a busy month since I last wrote!

I went home to the Midwest to celebrate the holidays with family.  We had lots of laughter, family gatherings, time spent relaxing, present exchanges, and good memories.  Highlights included going to the Indianapolis Symphony to see the annual Christmas Yuletide show as well as having lunch with a good friend to see her new engagement ring!  While being home for two weeks was wonderful, all good things come to an end and it was back to Boston on January 4th.

The past week and a half I have been working on my research without the distraction of classes.  I must admit, having such large blocks of time for research tasks was productive but also pretty strange.  I'm used to doing 20 different things at once.  For example, a year ago I was student teaching full time in a rural high school and writing/defending a senior thesis at the same time and the semester before that I was taking 5 classes, including a couple upper level geology classes, while TAing for another 2 courses, working as a planetarium operator, working on research, and doing classroom observation hours.  The chance to focus on just research...well it's been a while since that chance came along.

It's been a fairly eventful week and a half in regards to research.  I have now learned most of the garnet dissolution and lab techniques that we use frequently and my first actual garnet samples should be analyzed within the next couple weeks... well as soon as the TIMS is working again.  For those of you unfamiliar with the TIMS, it is the main analytical instrument that our lab uses to generate chemical data on garnet.  I don't want to get into all of the particulars of the machine's operation or purpose at the moment (I'll save it for a more extensive post with pictures to illustrate) but suffice it to say that the solution for fixing the instrument involved disconnecting all of the electrical connections and probes, rolling a 900+ pound magnet away from the instrument, and using heating pads, internal heating elements, and insulating blankets to literally bake the instrument to high temperatures to burn off any accumulated debris from years of use.  I got to help our lab tech. go through the steps to prep the instrument for baking and learned a lot about the instrument in the process!  I have also been doing major sample preparation in anticipation of a trip to Woods Hole Oceanographic Institute (WHOI) this coming Friday for preliminary chemical analysis.  Keep an eye out for a post next week on my adventure to Woods Hole!

Reflecting on a PhD Beginning

It's been two weeks since I last wrote for my blog and the fact that I am doing it now means one thing- finals are over!  Now that I have completed finals, I can officially call my first semester as a PhD student complete!  This post is mostly a summary of the classes and research progress I made in my first semester, plus some musings about the year as a whole.  I wrote it for myself as a way of providing perspective on what I have accomplished, as a benchmark to record my progress, to encourage myself for the work ahead, and as a preemptive New Year's reflection.  I decided to share it publicly since a few of you may be interested in a progress update and to encourage you all to pursue reflection on your own accomplishments.

These past couple of weeks have been packed with two major projects, two comprehensive finals, and quite a bit of research.  This semester I completed two classes- Geochemistry and Mathematical Modeling.  Geochemistry was largely review of the basics I learned as an undergrad. and reinforcement and further development of topics that I picked up and taught myself while working on my senior research project.  The class was fairly straightforward and clearly applicable to my area of study without any significant stretch of the imagination.  Math Modeling, however, was a totally different challenge.  It focused on the use of partial differential equations and modeling to examine everything from diffusion to advection to stress and strain and is one of two courses required for all geology PhD students at BU.  For a geochemistry student who had never opened Matlab (a computer program that uses basic coding and commands for math computation and modeling), never had a course in differential equations, and had not been in an advanced math course since senior year of high school, the whole idea was daunting.  If you had told me as an undergrad that my first semester in graduate school I would be required to take a course that covered these topics and that I would successfully produce a one-dimensional model that shows diffusion of Mn in garnet both analytically and numerically as my final project, I would have told you that you were crazy. As I went through the class it was often difficult to see any progress being made amid struggles to follow the lectures and to find any possible application of the class topics to my research area.  But now that the class is done, it is much easier to look back through the struggle and to appreciate how my thinking and skill sets have changed, how I have gained a new appreciation of diffusion and its relevance to the mineral analysis that I already love, and even how new topics that I was exposed to during this class could benefit my research in the future.  This is a large part of the reason that I pursued graduate work in the first place and it has been exciting to be able to see personal growth when I picked up a paper that went over my head six months ago that I can now understand or when I was able to correct a typo in Fortran code used in modeling that other scientists missed.

"All things good to know are difficult to learn."- Greek Proverb    

Besides classes, my other major task has been to begin the research which will eventually become my dissertation.  I've already started to share some of the research tasks that I have worked on this semester with you through my blog, and there are many others that I have been learning but haven't had time to share yet.  I have plenty of material for future science blog posts!  I am now one chemistry and one analytic step away from generating my first set of detrital garnet analyses.  I have done sample preparation on material from three different locations total, which will allow me to push forward their chemistry in coming months.  I have started a test that will be used to directly compare and analyze the accuracy of the ages produced by detrital garnet geochronology to the ages generated by the lab's currently accepted techniques for dating garnet from metamorphic rocks.  Not bad for 3.5 months and having to learn all the techniques from scratch, although I think it is the nature of the scientist to always wish for more progress. :-)

Exactly one year ago, I was a senior undergraduate student at a small private school in the Midwest.  I was submitting my finalized applications to graduate schools across the country, preparing to student teach during the final semester of undergrad. (Spring of 2011) and knew big changes were coming in my life.  Since then I completed one semester of full-time teaching experience in a rural high school, defended my senior thesis, graduated at the top of my class, chose a graduate program, went abroad for the first time to complete fieldwork in Scotland, moved across the country to Boston, and I have now completed a full semester as a PhD graduate student.  It constantly amazes me how much can happen in a year, and I can only imagine what this coming year is going to bring! (Here's hoping the coming year brings my name as a coauthor on a peer-reviewed, published paper!)

Metamorphosis of a Superhero

Spies go undercover, adopting a new set of clothing and a new appearance in order to fulfill their missions.  Superheroes have brightly colored suits, capes, and a wide array of weapons and gadgets at their disposal while they save the day.  Geochemists often have their own equivalent of the superhero costume or undercover spy clothing- they have clean lab gear!

Several weeks ago I shared a picture drawn by my best friend that shows me as a superhero named GeoKate.  Here it is again in case you missed it the first time:

This picture along with questions from several people about what I have to wear when working in the clean lab have inspired me to present a real-life view of GeoKate, who by attending grad. school is in training to become a geochemistry superhero.  Enjoy!

The Metamorphosis: From Ordinary Grad. Student to Clean Lab Superhero
Upon entering the outer room of the clean lab, the heroine leaves behind the tools of her everyday life (keys, phone, shoes, etc) and prepares to transform.  Winding her way deeper into the lab, she encounters the cloak room, and the metamorphosis begins.

1)  Shoes- Lab shoes not only prevent acid from damaging the heroine's feet, but add a stylish touch to the superhero uniform.

 2) Hair net- A stray hair in your lab beaker is definitely not acceptable.  Neither is having your hair in your face while you're flying.

3) Hood-  A key part of obscuring your identity, since it makes everyone in the lab look identical from most angles.

 4) Lab coat-  Besides the practical use of keeping her clothes clean while fighting crime and dissolving rock, it nicely doubles as a cape while in flight.  It also confuses all of the various evil doctors and villains who often use lab coats as their standard uniform.  They don't expect a superhero to wear one!

5) Face shield/goggles-  GeoKate is modeling the face shield here but most of the time wears the less extreme goggle option.  But sometimes you just need the extra protection and a bug guard while flying!

6) Gloves- Blue nitrile gloves.  Definitely an up-and-coming fashion trend for the functionality conscious.  No germs, no mess, and a splash of color that matches the shoes. Not to mention no fingerprints.....

  Voila! The metamorphosis is complete.  Now...off to save the day! (or learn more about garnet...)

Grains of Sand

About a month ago I told you about my piles of sand.  Now I am headed for single grains of sand and you are invited to follow along with my next science installment!

My last science installment followed the steps involved in generating several vials of sand with magnetic properties close to those expected for my mineral of interest- garnet.  This process narrows the search field, but unfortunately never yields a vial of pure garnet.  That's where the next step comes in.

The next step is known as hand-picking.  It takes place under a stereoscope, which looks like this:

Stereoscope on and ready to go

Basically, it's a microscope that allows the user to examine three-dimensional samples under varying magnifications and light intensities.  This particular scope is also outfitted with a digital camera for taking pictures of the individual sand grains when necessary.

The samples, which can be seen in the vials to the right of the scope above, are dumped into a weighing boat (the blue plastic dish the vials are in- above) or a clean glass dish.  The dish and sample are placed under the stereoscope.  Then I have to use the magnifying powers of the stereoscope, very fine tweezers, and my mineral identification skills to sort the garnet grains from all of the other grains of sand, proceeding one grain at a time.

PTFE-coated Tweezers, ink pen and lab notes for scale

I have two pairs of tweezers- one made from non-magnetic stainless steel and the other pair coated in PTFE (Teflon).  Both are considered needle-point and are essentially some of the finest tipped tweezers available.  They have to be...I am using them to pick up individual sand grains!  Why two pairs you ask?  The pair coated in Teflon is intended only for use with my detrital garnet grains, to minimize the exposure of the grains to unnecessary metal.  Contact with metal objects could, theoretically, contaminate my samples and skew my results since I am working with such extremely small sample volumes.  I am pretty sure that any potential impact of metal contact will be mitigated by later processing, but it never hurts to avoid the potential problem altogether when possible!  

Ultimately, each grain of garnet is individually picked out of my piles of sand using the tweezers and placed in a new vial containing only garnet from a single sample.  Generally, garnet is fairly easy to identify beneath the stereoscope's magnification, since it is pink to red to reddish brown.  Most of the other minerals that end up with it when grouped magnetically are nowhere near this color spectrum.

Hand-picking continues until I have gathered a vial with enough garnet to be analyzed.  This can take quite a bit of time, since each grain is selected individually.  Once enough grains are selected, it's off to the clean lab!  More on those adventures will be coming soon..... 

Of course, this is nowhere near an ideal system for mineral separation yet.  My original sand contains an extremely large volume of two minerals known as quartz and feldspar.  They are so abundant, that although magnetic separation should keep them far away from the garnet, they have permeated everything and to make matters worse, the feldspar is pink!  I am currently researching additional processing steps to add to our current mineral separation methods, such as heavy liquids and/or a water table, to eliminate this problem. Hopefully there will be posts in the future about new processes and procedures that I have added to our lab's capabilities to deal with these issues.

Piles of Sand

Am I doing any work or just exploring the city? What have I been up to in the lab?  I'm so glad you asked, and I have an answer for you this week.  Prepare yourself- this is a (lengthy) science update post!

I am now officially one month into my time here in Boston.  Besides adjusting to life as a grad. student, life in a new city, and my two classes for the semester (geochemistry and a mathematical modeling course), I have plenty of ambitious research goals for the semester.  In fact, I have at least four projects that I am supposed to be starting or working on at some point in the next couple months.  I have a feeling you'll hear about them over the coming months..or years.

But before I can produce large amounts of relevant data in the lab, I am currently in that joyous stage of being the newbie, the trainee, the person who has no idea how to do most of the routine procedures in my new lab and has to ask someone for help every time I come up against the next step.  Clearly there are some benefits to that situation (like being limited in what labs I have been trained in so therefore feeling no guilt at not spending every waking moment in the lab or the constant learning of new and exciting things) as well as drawbacks (like not being even remotely self-sufficient and making slow research progress).  I have been assured by my adviser that it could take me a good year to two years until I can confidently handle any and all of the research tasks expected of me- so I suppose I am doing well for a month in. It's all about perspective.

That being said, I am happy to share with you what I have accomplished this month in the lab.  Really, it all centers on making piles of sand.

Glen Clova, Scotland

The first of my four projects involves sand collected from a river flowing through Glen Clova, Scotland.  Glen Clova is a famous glacially-carved, U-shaped valley and is part of the type locality for the Barrovian metamorphic sequence.  I visited in June and collected the sample, along with my adviser and field assistant.  (If you missed my post on summer fieldwork and want to see more details on my trip to Scotland or pictures, check it out here.)  The current goal for the sample is to separate out the mineral garnet and attempt to establish an age for individual garnet grains.  This sample will be a part of the method development for my dissertation.  My overall PhD project is focused on developing a system for dating detrital (eroded and then redeposited elsewhere) garnets, which has essentially never been done and would open a whole new tool for geochronology.

The first step is taking my bucket of sand and separating out the grains of garnet from the overwhelming amounts of quartz, feldspar, and other minerals present.  While you could theoretically just sit there with tweezers and hunt through the bucket, that would be terrible and not very efficient.  Therefore, we can use properties of the minerals to separate them into different "piles."  Many geologists (and most prospectors) have gone through a similar series of steps as a part of the basic sample preparation that is my current lab activity.

The first step is to send the sand through sieves with different size mesh screens.  This divides the grains into piles with similar grain sizes.  This is important not only for later mineral separation steps, but allows me to gain an idea of the grain size distribution for garnet in this sample.  Since I am developing a new method that uses a single grain of garnet at a time, I would ideally like to find the largest grains that exist to start with, before working down to smaller grains.  Also, since my samples have much larger grains than what my lab is used to working with (finely crushed "pure" garnets), I got to determine that we need some sieves with larger mesh sizes and order them.  Thus, my first contribution to making my lab more versatile! Hooray!

Once the grains are separated by size, I have been using a Frantz electromagnetic separator to divide the grains based on magnetic susceptibility.  Most mineral grains are magnetic to at least a small degree, especially if you use a big enough electromagnet and set it appropriately.  The differences in magnetic susceptibility between minerals of different types allow sand to be separated into piles based on the degree of magnetism.

The Frantz I've been using the past couple weeks

Here's how it works:

1. Clean the machine thoroughly.  (You definitely don't want grains from the previous user's sample contaminating your sample!)
2. Turn on the magnet and set the desired level of magnetism.  Since I'm aiming for garnet, I usually start with a high setting to eliminate the least magnetic minerals and work my way towards gradually eliminating more magnetic minerals.  People who want to separate out other minerals may approach it differently.
3. Load whatever sample you wish to separate into the glass container that will feed the grains into the machine.  Usually you want to use a hand magnet on this sample before you load it, because that will remove one mineral (magnetite) that is the most magnetic and keep very magnetic grains from sticking to the magnet.
4. You can control how quickly the glass feeder container and a tray between the two portions of the electromagnet vibrate to control how quickly grains move through the magnet.  Grains fall out of the feeder (ideally basically one grain at a time so they don't influence one another) and move down a tray between the electromagnet.  The tray is tilted so that by gravity, grains prefer to move down the side away from the operator.  However, grains that are more magnetic than the magnet's current setting will be pulled up to the portion of the track closer to the operator.  The grains are then separated into two containers at the other end- the closer one being more magnetic and the one further away less magnetic.
5. Since I want garnet I continually rerun the pile collected in the container closest to me at a lower magnetic setting so that it is separated into two new piles.  This continues until I have one or two piles that have a larger proportion of garnet than any of the other piles.

Some people use heavy liquids or water tables to separate minerals by density and to reduce the amount of time required and increase the efficiency of the Frantz.  We have been discussing having me implement these strategies in our lab eventually, especially since I may have to separate relatively large amounts of sand.  We shall see what the future holds.

I also got to make another contribution to improving my lab's efficiency by constructing a "backboard" to keep my grains from bouncing out of the Frantz as they dropped out of the feeder.  Evidently the combination of larger grain size plus an old Frantz model leads to quite a few grains trying to jump ship before they head down the tray- regardless of how high or low the vibration of the feeder and tray is set.  I improvised a shield from weighing paper and label stickers- nothing like scientific McGuyvering.

That pretty much sums up month one in the lab.  So far it has been basic sample processing (all of which I actually did once upon a time as an undergrad. for a term project) but at least it's progress!  I'll share the next step for these piles of sand in an upcoming post.