395 XRay Lab Report

Aidan Leetz

Summary

No major issues encountered. A XRD sample AND ICP bead was made/run from a billet of material from EXP 395C.

Summary of analysis, not including any analysis of Standards and/or reference material.

Items Received:

• Heat Exchanger spare for Haskris

• 100g Metaborate

• Weighed Flux vials - 4 boxes *72 vials = 288 vials

• 1oz vials – 3 boxes*48 vials = 144 vials

Aeris

Corundum standard ran at the beginning and middle of the expedition, the data compared well.  A new Aeris parameter file was created, based on the parameters form 395C which was found in an archived tech report as well as the datasets made available from 395C. It was requested by the scientists to use the same parameters as 395C. The file is titled X395 5-100deg .25div 21min. The Aeris hardware setup was also kept the same: 20mm Fixed mask, 1/4° divergence slit, High beam knife.

The Si Standard run was completed before coring. The diffractogram compares well with the reference data. New reference diffractograms were created as the previous scans were done using different hardware and parameter settings to that which is specified.

The instrument had some issues, firstly at one stage after a long time of consecutive running, the instrument acted erroneously by appearing to perform two measurements at once. Only one sample was loaded but two samples on the screen showed the yellow key symbol. This froze everything but was resolved by initiating manual control and unloading the sample and powering off and restarting the machine.

The instrument still has its usual restart issue of the sample arm getting stuck when performing initial movements. It was noticed that the door closes/shutter closes too early and thus hits the loader arm causing it to be unable to move. This can be mitigated by the technician physically depressing the shutter/door whilst the loader arm is performing initial movements upon restart.

PXRF

The device itself, for the most part, functioned well. A key note is to monitor the battery, if the battery is even slightly depleted, it experiences issues whilst measuring. It flags “counts too low” and “battery too low” errors. The uploading of data seemed to be a slight issue. First of all the software (MUT and LIMS) doesn’t allow for standards to be uploaded. Understandably, this is due to the fact that the standards do not have core and section numbers (e.g 74R/2A) to populate the required fields, instead it has the name of the standard e.g BHVO-2. This could possibly something to look at for future as some scientists inquired about this. The Standard runs are still visible in the .csv and .tsv files.

Another persistent issue is that MUT does not upload the last measurement in a batch. For example, If you had to perform five measurements it will only upload the first four. The fifth one will be uploaded once more measurements follow it, but then the last measurement of the next batch does not get uploaded, and so forth. It is unsure what the issue is here and further investigation is required, perhaps something to with the position of characters in the .csv file. A standard was measured but not uploaded at the end so that the last data file could be uploaded.

Three rings were used by the three operators (technician and two scientists) and were shipped off.

The camera is also slightly out of alignment. It is doubtful that the technician is able to fix this, could it perhaps be sent away?

A few notes for archival purposes (future PXRF users, technicians etc.):

• The data will not upload if the TextID and sample type do not match. As an example, if the Sample Type field was set to “Standard” and a section half was measured with the usual TextID e.g SHLF10200010, the device will record and measure it as usual but this will not upload via MUT. Its an easy fix, just comb through the .csv and .tsv files find the run and edit the data.

• The data will not upload if the TextID was erroneously typed in small letters as opposed to the usual capitals

• Anything run as sample type “Standard” with the name of the standard in the Core/Section field e.g BHVO-2, will not upload

D4 Bruker and Haskris

Not used during this expedition as scientists requested the Aeris be used, for the purpose of being consistent with 395C. It was however kept powered on as it is suggested that it should not be left off for long periods of time.

Mettler Toledo Balances

This was used by the chem techs mostly, functions as it should.

Shatterbox

Functions as expected, no issues.

ICP Prep

Platinum crucibles 21,14, 20, 23 and 18 were sent back to shore to be recast, as they were quite damaged. A new set of quartz crucibles were made up as the old set was past the point of any further use. This mainly consisted of adding new 20ml crucibles and a few lids and 30ml crucibles.

SPEX Mixer/Mill

The mill incurred some issues on 399. The tension spring was apart in two pieces due to the clip ring failing at some point. This was replaced and put back together. All pillars were tightened as well. The mill then kept on blowing fuses after being turned for a few seconds, this was mitigated by cleaning and crimping electrical contacts. The entire mill was taken apart and cleaned, the motor was even opened up cleaned and inspected.

Additional Commentary

A few of the samples in the dataset are labelled as XRD_ACID. These samples underwent special sample preparation methods in an attempt to decarbonate them. The point was too remove as much carbonate minerals/phases as possible to be able to see/analyse any minor mineral phases that might be present. The methodology is listed below:

Standard Operating Procedure

Decarbonation of samples for XRD Analysis

Notes:

• The initial sample (prior to decarbonation) does not need to be completely dry (some natural moisture is irrelevant). Allow to dry on paper towel for a few minutes if very wet; or, if breaking up sample while damp/wet is difficult, dry as desired. Losing a little bit of sample during this part of the process will not affect the analysis.

• It may be difficult initially to estimate starting mass in a new lithology, so the first one or two samples may require some trial before an ideal initial sample mass is determined. Use more material to begin with when unsure.

• Exercise caution particularly during the initial phases of acid addition: chalk or ooze will react very energetically. Wear appropriate PPE even while working in the fume hood.

• Heating is unnecessary; temperatures over 50C may affect mineralogy.

• Buffer acidity should not fall below pH 5. Values slightly over pH 5 will not affect analysis, although it may take longer to remove the carbonate.

To Make Buffer Solution (1M Sodium Acetate buffer, from Sodium Acetate Trihydrate):

• Prepare 800 mL of deionized water in a suitable container.

• Add 136 g of Sodium Acetate Trihydrate to the solution.

• Check pH. Adjust solution to ~ pH 5 using dropwise addition of acetic acid. Record volume used to speed preparation of next batch of buffer.

• Add deionized water until the volume is 1 L.

Procedure:

1. Acquire appropriate sample mass (see table below). Break into small pieces so acid can penetrate and to speed the dissolution process.

2. Arrange necessary items in fume hood: 50 mL centrifuge tubes, rack, 5 mL pipette and tips, beaker for pipetting solution, buffer solution, waste container.

3. Place sample(s) in centrifuge tube(s).

4. Add 1 mL of deionized water (or none if sample is very wet).

5. Add buffer solution in increments of 5 mL, shaking lightly between. Add solution slowly initially as it may fizz. Add solution to 35 mL line.

6. Vortex sample and solution. Place on ‘hand shaker’ for 5 hours.

7. Centrifuge for 3 min at 3000 RPM. Decant supernatant. If supernatant is cloudy, centrifuge a little longer.

8. Pipette more buffer solution to tubes (to 35 mL line). Vortex until well-mixed. Place back onto shaker for 5 hours.

9. Centrifuge again for 3 min at 3000 RPM. Decant supernatant.

10. Add deionized water to centrifuge tube to 35 mL. Shake/vortex well. Centrifuge 3 min at 3000 RPM. Decant supernatant. Repeat for a total of three rinses. The last 2-3 rinses may be more difficult to centrifuge; supernatant may remain cloudy. If this is the case, centrifuge for 5 min, and use a thin rod to break up pellet if required after decanting water, ensuring to rinse any sediment on the stirring implement is rinsed back into the tube. If some cloudiness remains after 5 min in the centrifuge, decant and note that cloudiness remained.

11. Freeze dry sample and prepare as usual for XRD analysis.

Handy dandy conversion table to estimate sample mass required: