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Figure 2. Buehler diamond discs for polishing (use either one, or start with the courser grained and finish with finer grain but that is not necessary).

Figure 3. Labeled beaker with polished rock inside. 

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•  Put one Delrin disc on top of the weigh paper (Figure 10).

Figure 10. Delrin disk Added

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• Now place the second delrin disc on top of the sample (Figure 12). Again make sure the disc rests flat against sample (as flat as it can be).

Figure 12. Second Delrin Disk added

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After the sample has cracked remove the crushing unit. To remove the unit, loosen the 'pressure relief handle' (Figure 15C) by rotating it counter clock wise clockwise and press down on the toggle switch. The pressure gauge should read zero and the metal platform will lower down. Do not leave the platform up, always make sure to lower it back down after crushing a sample (you can use the jackscrew to lower the metal platform if it does not automatically fall once pressure is released). When the platform is level with the surface let go of the toggle and start unscrewing the jackscrew. Then open the door and remove the sample crushing set up. The pieces can be poured into a labeled bottle that will eventually hold the finely ground powder. From here the pieces will then be put into the Shatterbox vessels.

If pieces are still too large to fit in the shatter box vessel (<1cmsee Figure 21) then repeat the same setup and crush it again. Look out for and remove any pieces of the Delrin Discs that may have chipped off and gotten into the sample. Leaving pieces of the Delrin Discs in the sample will cause contamination.

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Normal Sounds: The shatterbox is extremely loud. The foam and strap surrounding the shatterbox helps keep it in place and minimize some of the noise.
Abnormal Sounds. If there are any metal on metal sounds shut off the shatterbox immediately. Something inside the shatterbox has probably come loose and will damage the inside of the container.

When the shatterbox cycle is done open the lid and remove the vessels, placing them on the counter. Open the grinding vessel and with clean tweezers take a bit of the powder and feel it against the inside of your wrist. The sample should feel like baby talc powder, if it does not, repeat the shatterbox cycle.

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Vessels must be cleaned in between samples and after all samples have been run for the day. Vessels should never be put away wet. This alters and tarnishes the vessel.

In Between Sample Runs

1. Wearing nitrile gloves, wash the individual pieces of the grinding vessels with DI water and a small piece of a scouring pad (no soap).
2. After each washed piece piece immediately spray it with isopropyl alcohol and wipe it down with a Kim Wipe. Do not use the ship's compressed air line to dry pieces as the air is too dirty.
3. Lay the pieces on, and cover vessels with Kim Wipes.

After the last run for the day1.

1. Take a scoop of quartz sand and put it in your vessel and run it as you would a sample for several minutes.

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1. Remove the vessel and empty out the sand. Scrub the pieces with DI water and a scouring pad. Then spray with isopropyl alcohol and wipe down with Kim Wipe.
   If your vessel is particularly dirty run a combination of quartz sand, a little hot water and detergent (Borax). This can be run for several minutes. A thick paste will form and you clean it with DI water and isopropyl as in the other cases.

Determining LOI

Loss on Ignition, or 'LOI', compares a mass measurement taken before and after a sample is subjected to extreme heat. Petrologists use LOI as an indication of degree of alteration. Low LOI values suggest relatively fresh, unaltered basalt; whereas high LOI numbers suggest alteration (clay, alteration minerals, etc.).
LOI is determined by weighing a small amount of the sample (~5 g) before and after ignition. Samples typically lose weight as water is driven off, though an iron-rich, water-poor sample may gain weight.

LOI is not required for all types of ICP Preparation. Check with the science party to determine if LOI is a desired measurement. If the science party does not want an LOI measurement move on to the section Making the Sample Bead.

Loss on Ignition

Determining a sample LOI comprises three procedures:

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 Place a large sheet of paper in front of the balances and place supplies here. For each sample you need weigh paper (Figure 33A28A), a scoopula (Figure 33C28C), and a quartz crucible set (Figure 33B28B). Clean the scoopula with isopropyl alcohol in between each sample as it has direct contact with the sample powder.



Figure 3328. Materials needed for weighing LOI. A. : Clean paper or kim wipe. B. : Crucible set. C. : Scoopula. D. : Samples

Setting up the Mettler Toledo Balances

Samples are weighed on the Mettler-Toledo Dual Balance. The Dual balance uses two weighing stations to compensate for shipboard motion: one a 'known' reference weight (Figure 34A29A) and the other an 'unknown' sample weight (Figure 34B29B). The balance takes a series of measurements and uses the average value as the final weight (for a more in-depth guide refer to the Balance User Guide on Cumulus). Each balance has a control panel plate, which constantly record records weight. These plates communicate with the "Mettler Balances" program.

Figure 3429. Mettler Balance Station located in the XRay lab. A. : Reference balance. B. : Unknown balance. C. : Sliding door. D. : Reference power module. E. : Unknown power module.
 

 Open the Mettler Balances program (Figure 3530). There are multiple panes and parameters that are set before we start measuring.

Figure 3530. Mettler Balance program window. A. : Graphical measurement window. B. : Final weight panel. C. : Statistics panel. D. : Weigh. E. : Tare. F. : Halt. G. : Options panel. H. : History panel.

Graphical Measurement Window: Shows a line graph of the live-time measurement weight and the running average weight.
Final Weight Panel: Displays the Final Weight after all measurement counts have been made.
Statistics Panel: Shows the average weight adjusting with time.
Counter Weight: Enter in the reference weight Counts: The elapsed amount of measurements
Tare: Shows and applies the tare or 'zero' value.
Sample ID: Name the sample being measured.
Commands Panel: Executable commands
Weigh: Starts measurement
Tare: Determines the 'zero' weight. This value is applied to the final weight.
Halt: Stops a measurement before it has gone through all counts
History Panel: Shows statistics on all measurements taken. This file can be exported into an excel file by using the 'Export' button. Note: The 'Export CSV' file does not work.
Options Panel: Editable measurement parameters. We measure using the 'Counts' feature. 'Counts' is active when the dot is blue. Change the number of counts or measurements the balance takes here.
At the beginning of a series of measurements, tare the balances. To do this first make sure that the 'Counter Weight' field is set to '0' and then set the 'Count' value. The 'Count' is dependent of the sea state: 600 for calm waters and 1000 counts for rough waters. If seas are too rough than wait until the weather settles before continuing to measure.
A rule of thumb is that the measurement of a known reference mass shouldn't have a larger deviation than the accuracy desired. For example, our accuracy is +/- 0.05 grams; weigh a reference mass in the unknown balance that is close to the masses you are measuring (e.g., 25 grams) and perform the measurement with the appropriate counterbalance mass in the reference balance pan. You should get a final mass of 24.95—25.05 grams.
Once parameters are set, select the 'Tare' button. When the tare is complete the 'Final Weight' Section turns orange and the 'History' Section updates (Figure 3631).

Figure 3631. Mettler Balance program window showing a tare calculation.

Put in a reference weight into the "Reference' balance. With the tweezers, select the 20g weight and place it in the center of the 'Reference' balance (Figure 3732). To have a more accurate measurement, the reference weight should be close to the expected 'Unknown' sample weight (roughly ~20g).

Figure 3732. Reference weights. A. : Weights. B. : Tweezers.

Weighing Crucibles

 The quartz crucibles have three sections: an outer (or large) crucible, an inner (or small) crucible, and a lid (Figure 3833).

Figure 3833. Crucible components. A. : Outer (large) crucible. B. : Inner (small) crucible. C. : Lid.

The inner crucible holds the sample material and is the only piece that is weighed. They are assembled as seen below with the inner crucible inside of the outer crucible and the lid sitting over the entire unit (Figure 3934). Crucible sets (large, small and lid) are engraved and lettered and should be kept as a set. For example, Crucible lid 'A' should always be run with large and small crucible 'A'. If a crucible is unlabeled use a diamond-tipped pen to etch in an unused lid.

Figure 3934. Complete and assembled crucible unit.

Weight measurements are recorded in an excel spreadsheet which will be uploaded to LIMS at the end of an expedition (Figure 4035). Open the excel spreadsheet titled 'LOI Template' found in Local Disk > DATA and save the spreadsheet in Local Disk > DATA > IN as 'EXP # LOI'Desktop > XRD-ICP Prep Documents >LOI spreadsheets.

Figure 4035. LOI spreadsheet.

The spreadsheet has multiple columns to fill in.'SITE', TEXT ID', 'CORE/SECT/INTERVAL', 'CRUCIBLE ID', 'CRUCIBLE WT', 'CRU+FRESH SAMPLE WT', and 'CRU+IGN SAMPLE WEIGHT'. 'SAMPLE WEIGHT', POST IGNITION LOSS', and '%LOI' are calculated values based on the weights entered in columns E – G.
The first measurement taken will be the initial weight of an empty crucible. To complete this measurement, open the side door and place an empty inner crucible in the center of the 'Unknown' balance (Figure 4136). Record the number or letter etched onto the crucible in the excel spreadsheet under 'Crucible ID.'

Figure 4136. Weighing an empty inner crucible.
 

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Weigh out 5 grams of sample powder into the quartz crucible within +/- 0.05g (Figure 4237). The total weight should be the crucible weight + 5 grams within +/- 0.05 grams. For example, a crucible weighs 14.32g, thus the total weight plus the sample will be between 19.27 – 19.37g. We use 5g because it is a good representation of the sample and it fills the crucible  appropriately. You will find that you will loose some of the sample due to it sticking to the qtr crucible when you are finished with the LOI.

 Note: If there is only a small amount of material, you can use less but the %LOI error will be larger. 

Figure 4237. Crucible with approximately 5g of sample. Pre-ignition measurement

When the sample is close to this range click 'Weigh.' Press 'Halt' to stop the measurement and either add or remove sample if needed, and then click on 'Weigh' again to take a new measurement. 

When a sample's final weight is within the allowable range, record the 'final weight' value into the spreadsheet under 'CRU + FRESH SAMPLE WT'.

Carefully remove your sample from the balance. Place your crucible into the larger quartz holder and cover with a lid (Figure 4338). Repeat this process for all samples. After all samples have been weighed and recorded, take samples from the desiccator and bring over to the muffle furnace in the Chemistry Lab.

Figure 4338. Complete crucible unit with sample, ready for ignition.

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Bring crucibles over to the Muffle Furnace (Figure 4439). There is a wooden tray to assist the transferor crucibles from one lab to the other. Turn the power switch on and the control panel will illuminate.

Figure 4439. The Thermolyne Muffle Furnace. A. : Power Switch. B. : Control Panel. C. : Door handle.
 

Confirm with scientists, what temperature and how long samples should be run for. Below is a quick reference guide:

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A common program is an increase in temperature of 3°C/min to a target temperature of 900°C and a hold of one hour. Then ramp up at a rate of 3°C/min to a target temperature of 1025°C and hold for four hours. This ramp cycle is already programmed into the furnace and corresponds to 'Program 1'. To check or edit a program see additional guides attached to the furnace itself. It is also possible to run the furnace manually without a ramp up cycle. Discuss with scientists their preference. 

Either enter the desired temperature manually or select your program. If you are running the furnace manually, enter the desired temperature; no other buttons or steps are needed. If selecting a program, press and hold 'Run' (Figure 4540).

Figure 4540. Control Panel on Thermolyne Muffle Furnace. A. Actual temperature. B. Desired/ Set temperature. C. Run/ stop button. D. Auto run button. E. Page button. F. Scroll button. G. Down button. H. Up button. 

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Post-ignition measurements should be taken immediately soon (within an hour) after removing crucibles from the furnace. Failure to do so will disrupt the LOI values. Reweigh the crucible plus the ignited sample to determine how much weight was gained or lost. Follow the same weighing procedure as in Pre-ignition Weighing.

1. Record the final weight in the excel spreadsheet under 'CRUCIBLE + IGN SAMPLE WT'. The spreadsheet will populate the columns 'Post Ignition Loss' and '%LOI'.
2. The formula used to calculate LOI is:

%LOI = 100 x (weight change during ignition)/ (fresh sample weight).

Note: By convention, weight lost during ignition is recorded as a positive LOI value; whereas weight gained is recorded as a negative LOI value. Report the results to 2 decimal places.

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Open the Excel File 'LOI Spreadsheet Upload Template' in Local Disk > DATA (Figure 46). Put your LOI information into the spreadsheet following the example format. Fill in the Text ID, Analysis, Replicate, Crucible number, and all weights and units including the %LOI.

Figure 4641. LOI Spreadsheet Upload Template.

Open up the program ‘Spreadsheet Uploader’ Pinned to the Taskbar (Figure 4741). 

Figure 4742. Spreadsheet Uploader Icon.

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Some crucibles will develop a thin white cloudy film, become spotted, or start flaking. If any of these things happen throw thrash the crucible away in the sharps container. When the crucible undergoes one of those changes the quartz has started to react at high temperatures, and could start contaminating the sample.

Making the Sample Bead

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sample.

Making the Sample Bead

• In a vial, mix 400 mg lithium metaborate flux (pre-weighed onshore) with either ignited or non-ignited powdered sample, check with the science party to determine which sample type should be used. Typically we use unignited powder as that is how our standard beads are prepared and what correlate to the certified values.   This  This step is typically completed by the chemistry technicians.
• Fuse both sample powder and flux into a glass bead (Figure 2843). Dissolve the bead in nitric acid. This solution will be further diluted and analyzed by the ICP.

Figure 2843. Fused glass bead. 

• An analytical procedural blank of Flux is prepared identically to the samples, with the exception that only . The 0.4 g of flux (the pre-weighed onshore amountflux) is fused with 10µL 0.172 mM of LiBr and dissolved. An additional 0.1 g of flux is NOT added to mimic the TDS of the 0.5 g mix of sample + flux because this would provide an inaccurate quantitation of the impurities introduced by the amount of flux used in preparation of the unknowns.

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Collect platinum crucibles, platinum tipped tongs, 0.172 LiBr, and pipette tips from the safe above the Bead Maker (Figure 2944). Get the 10-100ul pipette and teflon spatula from the drawer and clean with isopropyl alcohol. Have a tray of samples that need to be fused and an empty tray for finished beads.

 

Figure 2944. Bead making supplies. A. : Platinum tipped tongs. B. : Platinum crucibles. C. : 0.172 Libr wetting agent. D. : Pipette. E. : Teflon spatula. F. : Pipette tips. 

Turn 'On' the Bead Maker (Figure 3045; switch on the right side of the instrument). 

Figure 3045. Beadmaker. A. : control panel. B. : Site of platinum crucible. C. : View port window. D. : Fan to cool platinum crucible. E. : Ceramic plate used for dislodging the fused bead.

Next, turn on the water (Figure 3146; 3247). The handle is to the left of the machine on the wall. Raise the handle slightly to turn it on. You will hear a small click once it is in the 'on' position. Now the 'Water' and 'Ready' indicator lights should be on. Do not run any samples unless these lights are on.

Figure 3146. Water in off position.

Figure 3247. Water in on position.

1. Lay a large Kim wipe and a piece of weigh paper down next to the Bead Maker. Unwrap a platinum crucible and place it on the weigh paper. Pour the powder mix into the crucible. The sample should evenly cover the bottom.
2. Pipette 10 µL of 0.172 mM LiBr wetting agent into the center of the sample powder.
3. Open the Bead Maker lid and place sample inside the sample holder. The short wide crucible will fit directly; whereas, the tall narrow crucible will need an additional ceramic ring (no longer have these?).
4. Close the lid. Double check both indicator lights are on. Press 'On' to start the program. The process will take 12 minutes and the sample is heated in three stages:
   • Stage 1:700°C for 2 min
   • Stage 2:1050°C for 5 min,
   • Stage 3: 1050°C in agitation for 5 min.
5. Be prepared to remove the crucible as soon as the timer is donereaches 0. The material hardens very quickly so be ready with safety glasses, gloves, and the platinum tipped tongs before the final stage has finished.
6. With the Pt-tipped tongs, lift out the crucible and swirl the contents around to get the entire sample into one bead. Wear eye protection! The bead is very hot and rapid cooling can cause it to shatter and fly out.
7. Place the crucible on its cooling rack. When seated properly the red light behind it will start flashing. When the flashing stops the bead and crucible have bedmaker beeps it should be finished cooling down.
8. Place a sheet of 6x6 weigh paper on the ceramic plate. Take crucible from the cooling rack and prepare to flip it upside down on the paper to extract the bead.
9. With crucible in hand flip over and give it a firm whack on the weigh paper. The bead should pop off without much resistance. Put the bead back into the vial that contained the flux.
10. If there are small pieces of bead left behind you can use your Teflon spatula to try pry it off. Do not use too much force. The platinum is malleable and will get scratched and damaged if put under too much force. If it still remains, make a note of the sample number and inform the chemistry technician. The residue (if any) should come off during the cleaning process.
11. Repeat process for all samples.
12. Hand off all beads to the chemistry technicians to continue on with the ICP analysis.

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1. Rinse crucibles with DI water.
2. If beads are stuck to the bottom, sonicate with DI water for 30 min or more.
3. Place crucibles in HNO3 10% bath for 12 hr. If you notice any signs of residue, leave in the acid bath for longer.
4. Clean a Tupperware container with isopropyl alcohol. Lay down sheets of paper towel and large kimwipes.
5. Take crucibles out of the acid bath and rinse with DI water 3 times. Place crucible in the container. If the crucibles require polishing, see Polishing the Platinum Crucibles.
6. Cover all crucibles with a large Kimwipe and place in the drying oven in the Chemistry Laboratory. Leave overnight.
7. When dry remove crucibles and bring into the XRD laboratory. Wrap each crucible in a small Kimwipe and and place back in the safe. Lock the safe after all crucibles have been put back.

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