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Collect platinum crucibles, platinum tipped tongs, 0.172 LiBr, and pipette tips from the safe above the Bead Maker (Figure 30). 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 30. Bead making supplies. A. Platinum tipped tongs. B. Platinum crucibles. C. 0.172 Libr wetting agent. D. Pipette. E. Teflon spatula. F. Pipette tips. Figure 46. Bead making supplies
Turn 'On' the Bead Maker (Fig. 31; switch on the right side of the instrument).
Figure 31. 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.
Turn 'On' the Bead Maker (Fig. 46; switch on the right side of the instrument).
Next, turn on the water (Fig. 4732; 4833). 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 4832. Water in on off position.
Figure 4733. Water in off on position.
- 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.
- Pipette 10 µL of 0.172 mM LiBr wetting agent into the center of the sample powder.
- 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.
- 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.
- Be prepared to remove the crucible as soon as the timer is done. The material hardens very quickly so be ready with safety glasses, gloves, and the platinum tipped tongs before the final stage has finished.
- 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.
- 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 finished cooling down.
- 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.
- 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.
- 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.
- Repeat process for all samples.
- Hand off all beads to the chemistry technicians to continue on with the ICP analysis.
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...
...
Cleaning Platinum Crucibles
- Rinse crucibles with DI water.
- If beads are stuck to the bottom, sonicate with DI water for 30 min or more.
- Place crucibles in HNO3 10% bath for 12 hr. If you notice any signs of residue, leave in the acid bath for longer.
- Clean a Tupperware container with isopropyl alcohol. Lay down sheets of paper towel and a large kimwipes.
- 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.
- Cover all crucibles with a large Kimwipe and place in the drying oven in the Chemistry Laboratory. Leave overnight.
- 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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Polishing the Platinum Crucibles
It may
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It may be necessary to polish the crucibles to remove scratches. Do this no more than once per expedition because polishing thins the platinum and in time the crucible will crack. A polishing machine is located in the ICP prep area.
- Wrap a silk cloth (like the cloth used to clean eyeglasses) around the polishing nozzle.
- Apply a diamond paste (Grade 30, found in Thin Section Lab) to the front of the silk-covered nozzle and place the crucible over the nozzle.
- Turn polisher on and polish the crucible bottom for ~30 s (the bottom will be shiny). Be careful because the crucible will get hot. Do not try to remove any deep scratches – the crucibles are not that thick. The least amount of polishing the better.
- Clean the crucibles with isopropyl alcohol and put in 10% HNO3 bath for 12 hr.
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Using the LOI Furnace to Make Sample Beads
If the bead maker breaks, use the LOI furnace to make beads.
Caution! Safety is a major issue with this procedure; use proper personal protection equipment and note where the nearest fire extinguisher is located.
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- Place the sample crucible on a ceramic plate to cool. These crucibles are very hot and may burn anything near or under them. Take appropriate precautions.
- Repeat this procedure until all samples are completed.
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...
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Determining LOI
Loss on Igntion, 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.Anchor
...
Loss on Ignition
Determining a sample LOI comprises three procedures:
- Pre-ignition weighing
- Igniting samples
- Post-ignition weighing
...
...
Advice on LOI Procedures (from Exp. 366 Methods)
...
Shipboard
...
sample
...
preparation
...
and
...
LOI
...
determination
...
procedures
...
described
...
in
...
Murray
...
(2000)
...
and
...
updated
...
in
...
recent
...
IODP
...
Proceedings
...
volumes
...
(e.g.,
...
Reagan
...
et
...
al.
...
[2015
...
]
...
for
...
Expedition
...
352)
...
are
...
appropriate
...
for
...
a
...
range
...
of
...
sediment
...
and
...
rock
...
compositions,
...
but
...
some
...
care
...
must
...
be
...
taken
...
with
...
unusual
...
sample
...
matrixes.
...
As
...
an
...
example,
...
attempting
...
sample
...
ignitions
...
on
...
carbonate-rich
...
materials
...
can
...
lead
...
to
...
spurious
...
results
...
and
...
issues
...
with
...
contamination
...
if
...
quartz
...
crucibles
...
are
...
used
...
for
...
sample
...
ignitions
...
because
...
carbonates
...
will
...
react
...
with
...
quartz
...
upon
...
heating
...
to
...
both
...
devitrify
...
and
...
decompose
...
the
...
crucible.
...
Alumina
...
ceramic
...
crucibles
...
may
...
be
...
better
...
for
...
carbonates
...
but
...
risk
...
contamination
...
for
...
Al
...
and
...
potentially
...
other
...
elements
...
due
...
to
...
spallation
...
over
...
time.
...
Maximum
...
ignition
...
temperatures
...
of
...
1000°C
...
and
...
higher
...
are
...
appropriate
...
for
...
ultramafic
...
and
...
some
...
mafic
...
igneous
...
materials
...
but
...
may
...
result
...
in
...
sample
...
sintering
...
and/or
...
sticking
...
to
...
some
...
Si-
...
or
...
Ca-rich
...
materials.
...
Ignition
...
temperatures
...
of
...
<850°C
...
are
...
inadequate
...
to
...
decompose
...
carbonate
...
minerals
...
in
...
sediment
...
samples,
...
even
...
if
...
samples
...
are
...
held
...
at
...
temperature
...
for
...
several
...
hours.
...
In
...
general,
...
igniting
...
samples
...
to
...
at
...
least
...
900°C
...
as
...
a
...
maximum
...
temperature
...
is
...
advisable
...
to
...
decompose
...
all
...
volatile-bearing
...
phases
...
and
...
obtain
...
reliable
...
measures
...
of
...
LOI.
...
Pre-ignition Weighing
Apparatus and Materials
- Mettler Toledo Dual
...
- Mettler Toledo Dual Balance
- Acid Washed Quartz Crucibles
- 4x4 Weigh Paper
- Reference Weights
- Thermolyne Muffle Furnace
Clean the balance area including the balance plates inside the balance. Any dust or particles on the plate could throw off the weight measurements. Before beginning make sure there are enough acid washed quartz crucibles for your samples. The crucibles are located in the XRay X-Ray lab in a plastic container labeled 'Acid Washed Crucibles'. Wear gloves while handling the crucibles.
Place Place a large sheet of paper in front of the balances and place supplies here. For each sample you need weigh paper (Fig. 29A34A), a scoopula (Fig. 29C34C), and a quartz crucible set (Fig. 29B34B). Clean the scoopula with isopropyl alcohol in between each sample as it has direct contact with the sample powder.
Figure 2934. Materials needed for weighing LOI. A. Clean paper or kim wipe. B. Crucible set. C. Scoopula. D. Samples
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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 (Fig. 30A35A) and the other an 'unknown' sample weight (Fig. 30B35B). 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 weight. These plates communicate with the "Mettler Balances" program.
Figure 3035. 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 36). There are multiple panes and parameters that are set before we start measuring.
Figure 36
Figure 31. 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. 
Open the Mettler Balances program. This window will open
. There are multiple panes and parameters that are set before we start measuring.
Graphical Measurement Window: 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 (Fig. 32). The and the 'History' Section now has its first value added in updates (Fig. 3237).
Figure 3237. Mettler Balance program window showing a tare calculation.
Figure 33. Reference weights. A. Weights. B. Tweezers.
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. To have a more accurate measurement, the reference weight should be close to the expected 'Unknown' sample weight (roughly ~20g).
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Figure 38. 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 (Fig. 39).
Figure 39. Crucible components. A. Outer (large) crucible. B. Inner (small) crucible. C. Lid.
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Figure 34. Crucible components. A. Outer (large) crucible. B. Inner (small) crucible. C. Lid.
Figure 35. Complete and assembled crucible unit.
The quartz crucibles have three sections: an outer (or large) crucible, an inner (or small) crucible, and a lid (Fig. 34). 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 (Fig. 3540). 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 idlid.
Figure 36. LOI spreadsheet40. Complete and assembled crucible unit. 
Weight measurements are recorded in an excel spreadsheet (Fig. 36) which will be uploaded to LIMS at the end of an expedition (Fig 41). Open the excel spreadsheet titled 'LOI Template' found in Local Disk > DATA and save the spreadsheet in Local Disk > DATA > IN as 'EXP # LOI'.
Figure 41. 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 (Fig. 37). To complete this measurement, open the side door and place an empty inner crucible in the center of the 'Unknown' balance (Fig. 3742). Record the number or letter etched onto the crucible in the excel spreadsheet under 'Crucible ID.'
Figure 3742. Weighing an empty inner crucible.
Close the door and click 'Weigh'. Wait for the counts to finish and then record the 'Final Weight' in the spreadsheet under 'Crucible Wt'.
...
...
Weighing Sample
Weigh out 5 grams of sample powder into the quartz crucible within +/- 0.05g (Fig. 3843). 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.
Figure 38. Crucible with approximately 5g of sample. Pre-ignition measurement
19.37g.
Note: If there is only a small amount of material, you can use less but the %LOI error will be larger.
Figure 43. Crucible with approximately 5g of sample. Pre-ignition measurement
When the When it looks like your sample is close to this range click 'Weigh.' You can always press Press 'Halt' to stop the measurement and either add or remove sample . If you press 'Halt' re-click 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 (Fig. 3944). 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 3944. Complete crucible unit with sample, ready for ignition.
...
...
...
Igniting Samples
Samples are ignited in the Thermolyne Muffle furnace located in the Chemistry Laboratory. The entire ignition cycle takes approximately 20 hours. After ignition, samples need to be taken out when they come down to ~ 50°C-200°C. If the samples sit for too long they will reabsorb moisture and the 'Post-Ignition Weight' will be inaccurate. Time this accordingly.
...
Bring crucibles over to the Muffle Furnace (Fig. 4045). Turn the power switch on and the control panel will illuminate.
Figure 4045. The Thermolyne Muffle Furnace. A. Power Switch B. Control Panel C. Door handle.
Confirm with scientists, what temperate temperature and how long samples should be run for. Below is a quick reference guide (Fig. 41).:
Material | Ignition Time at °C |
Basalts | 4 or 5 hr at 1025°C |
Si-rich sediments | 4 or 6 hr at ~900°C |
Samples with:
| 6 hr or more at XXX°C |
...