Table of Contents

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Rock samples are prepared for ICP analysis using the following procedures on each sample:

1. Cut to size (see Cutting Samples to Size below)
2. Polish (see Polishing Samples on Diamond Wheel below)
3. Clean (see Cleaning Samples below)
4. Dry (see Drying Samples below)
5. Crush (see Crushing Samples in the X-Press in XRD Sample Preparation Hard Rock )
6. Grind (see Grinding Samples in the Shatterbox in XRD Sample Preparation Hard Rock)

Cutting Samples to Size

To cut samples for the X-Press, use the splitting room rock saws (located in the Core Deck) following these guidelines:

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Post-ignition measurements should be taken 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:

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Uploading LOI Data To LIMS

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Open the Excel File 'LOI_Spreadsheet Upload Template' in Local Disk > DATA (Figure 41). Put your LOI information into the spreadsheet following the example format. Fill in the following:

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>LOI > LOI_Spreadsheet.xlsx

The spreadsheet has three sheets:

• The first sheet is as follows:

• The second sheet is for repeats
• The third sheet is the format for uploading the data using the spreadsheet uploader (Figure 41)

Put your LOI information into the spreadsheet following the example format. Fill in the following:

• Text ID: e.g., WDGE11258831 (Note: capital letter matters)
• Analysis: LOI
• Replicate: 1 (usually)
• crucible_number: Crucible ID (e.g., A, B, F...)
• crucible_preignition_mass: crucible mass only (small inner crucible) (component unit: grams)
• crucible_and_preignition_sample_mass: inner crucible with fresh sample before ignition (component unit: grams)
• crucible_and_postignition_sample_mass: inner crucible with ignited sample after ignition (component unit: grams)
• loi_percent: LOI in % (component unit: none; the value is already a percentage)
• reference_mass: sample mass (calculated difference) (component unit: grams)
• comment: specify temperature and time used for LOI (e.g., 950 deg C for 4 hours; used during Exp 391)

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Figure 41. LOI Spreadsheet Upload Template.Template 

Open up the program ‘Spreadsheet Uploader’ Pinned Spreadsheet Uploader Pinned to the Taskbar (Figure 42). 

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Figure 42. Spreadsheet Uploader Icon.

Copy and paste your spreadsheet into that uploader. Click the 'Edit' button and 'Validate Sheet'. This checks and highlights any errors that need to be fixed. When the spreadsheet comes up clean, click 'Lims' and 'Upload'. The sheet will turn green when the measurements are successfully uploaded. The data is now in LIMS under Chemistry > ICP-AES Solids >Expanded LOI.

Cleaning the Quartz Crucibles

1. Wash the crucibles with DI water and a small piece of a scouring pad (no soap).
2. Rinse several times with DI water.
3. Place crucibles in a 10% HNO₃ bath for 12 hr.
4. Rinse 3 times with DI water after the acid bath.
5. Dry the crucibles in the oven at a maximum temperature of 60°C.

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Figure 43. Fused glass bead. 

• An analytical procedural blank of Flux is prepared identically to the samples. The 0.4 g of flux (the pre-weighed flux) 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.

Making beads - protocol used during Exp 391

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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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