...
Rock samples are prepared for ICP analysis using the following procedures on each sample:
- Cut to size (see Cutting Samples to Size below)
- Polish (see Polishing Samples on Diamond Wheel below)
- Clean (see Cleaning Samples below)
- Dry (see Drying Samples below)
- Crush (see Crushing Samples in the X-Press below)
- Grind (see Grinding Samples in the Shatterbox below)
Cutting Samples to Size
To cut samples for the X-Press, use the splitting room saw rock saws following these guidelines:
- Cut samples to ~1–2 cm in length and width. Avoid cutting irregular pieces; ideal samples are cubes. Cut the first samples small to get a feel for rock hardness.
- Avoid veins, infilled vugs, etc.
- Remove as much contaminated material as possible.
- Contact the petrologist(s) if cutting reveals unexpected features.
Notes about altered samples:
- It may be desirable to hand-pick and separate alteration material such as vesicles and/or veins from whole-rock basalt.
- Speak to the petrologist about this that method if alteration is visible.
Polishing Samples on Diamond Wheel
To Polishing the samples remove contamination ( caused by drill bit, saw blade, or other unwanted material) and clean the samples, grind . Grind each surface (each outer side) on a high-speed, diamond disc.
Apparatus and Materials
- Buehler Grinder/Polisher
- Diamond grinding disk
- Sample Beaker
Each sample will correspond to one beaker; collect as many beakers as needed. Beakers need to be cleaned (DI water and isopropyl alcohol) and labeled ( ex. 1, A, or sample label).
Next start the grinding process using the Buehler grinder located in the Xray prep area of the thin section lab (Figure 1).
Note: The diamond disc is attached to a magnetic disc which is then placed on the wheel plate. . Diamond disks are located on the stud shelf in ICP prep. Use the silver or purple diamond disk.
Figure 1: Buehler Grinder Polisher. A. On/Off switch B. Power Indicator light C. Timer On/Off button D. Water On/Off switch E. Water flow control knob F. Disc speed control. G. Stop/Start. H. Emergency Stop.
To start the polisher flip the 'On' switch in the back (Figure 1A). The power indicator light (Figure 1B) should illuminate. Press the timer on/off button (Figure 1C) to get continuous disc rotation. Turn the water on by flipping the 'Water' switch to the 'On' position (Figure 1D). The water flow can be adjusted by turning the knob shown in Figure 1E.
...
Polish the rocks with a Breuler diamond disc (Figure 2) until they're completely smooth and round on all edges. The purpose of grinding on a diamond disc is to remove any possible contaminates caused by the drilling mud (or drill bit) along with or the rock saws in the splitting room. There should be no pits or jagged corners. Put the rock into a labeled beaker (Figure 3) and polish the next sample. Do this for all samples and then move on to 'Cleaning Samples'.
...
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.
...
Apparatus and Materials
- Sonicator with basket
- Beakers
- 70% Isopropyl Alcohol
- Tray(s)
Pour either DI water or isopropyl alcohol (70%) into the beaker to cover the sample. Check with the scientists for their preference in of solution. There should be enough liquid in the beaker to keep the sample from floating in the sonic bath (Figure 3Sonic Bath without basket Figure 4).
Figure 4. Sonic Bath
Fill the sonic bath (Figure 4) with a little bit of water and place beakers inside. Sonicate for 15 minutes. You should notice the water becoming cloudy from residue being shaken off the samples. Then follow the wash sequence below:
- Decant as much of the liquid as possible
- Sonicate again with DI water for 10 min.
- Decant liquid into the sink
Repeat the rinse cycle until the water is clear. If the samples are soft and/or clay rich, they won't will not reach the "clear water" state. Continuing to sonicate will only dissolve the sample. If after 3–4 washings, the water still isn't clear, go to the next step. After the final rinse, decant as much water from the beaker as possible.
...
This step requires at least 12 hours and therefore should be done towards the end of your shift. Turn oven on (Figure 5) and adjust the dial to about 110°C . The dial should always be set at that temp. Turn on and confirm the oven temp via the thermostat inside the oven(this is marked on oven, or you will have to turn on oven a couple hours before and use the thermostat inside to get the temperature correct. It is important to not overheat the sample as it may affect some minerals. Less Temperatures less than 110°C is ok, but it may take longer than 12 hours for the sample to dry.
Apparatus and Materials
- ICP Prep Oven
- Samples
Note: The ICP oven should be kept clean at all times, as samples are left open and are susceptible to contamination. The ICP oven should only be used for ICP samples. If the oven shows any sign of rusting, please notify the ALO as a new oven will need to be ordered.
...
Figure 7: Materials needed for assembly of ‘crushing unit’. A. ) Weighing Paper 6”x6”. B. ) Core Liner. C. ) Two Delrin Discs. D. ) Stainless Steel Base. E. ) Aluminum Die.
Put on gloves and 'wash' your gloved hands with isopropyl alcohol. Clean the crushing supplies with isopropyl alcohol and set them down on the clean surface. Collect sample beakers from the desiccator. Put a piece of parafilm over each beaker and bring them over to the X-press. Now that the X-press area is clean and the samples are in the lab, assemble the crushing unit as follows:
...
- Now slip the piece of core liner over all the pieces and resting sit it inside the stainless steel base (Figure 14). This contains the sample pieces inside the unit.
Figure 14. Core Liner added
...
Figure 15: Overview of the X-Press. A. ) Metal platform sample rests on. B) Jacksrew. Jacksrew C. ) Pressure Relief Handle. D. ) ‘On’ toggle. E. ) Pressure Gauge.
Place the crushing unit inside the X-Press in the middle of the metal platform (Figure 15A). Put in the sliding polycarbonate door down when crushing samples. Tighten the jackscrew (Figure 15B) until it rests firmly against the aluminum die. Tighten the 'pressure relief handle' with a clockwise turn (Figure 14C15C).
Note: The polycarbonate door sits on two interlock switches that enable operation. If the door is not fully closed or pressing down on these switches the machine will not work.
Crush the sample by continuously holding down the toggle switch (Figure 14D15D). The motor and pump can be heard and the pressure will rise (Figure 14E15E). Once the desired pressure is reached about 5tons the toggle can be released and the sample will sit under that pressure. Do NOT leave a sample under pressure for any reason. For For most samples ~5 tons of pressure is enough force to crack it. If you find the need to go near 10 tons, try rotating the sample onto another side and repeat the process again. Taking the pressure up greater than 10 tons can cause the disks and the core liner to shatter. Contaminating the samples and creating a safety hazard.
...
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 and press down on the toggle switch. The pressure gauge should read zero and the metal platform will lower down. Do 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 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 unitsample 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 (<1cm) 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.
...