Heavy Liquid

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ID

heavy_liq_2582_float

Requires

heavy_liquid_setup heavy_liquid_calibrate heavy_liquid_cleanup

Description

Brief description of the overall procedure. This should include important details so that the procedure could be replicated.

Procedure

Before you begin your LST heavy liquid separations you must follow these procedures:

  1. Completely clean the LST Station. This entails the counter top, as well as all glassware. Dried drips and patches of LST are not acceptable. Please clean up after yourself. The LST costs over 1500/bottle so every drop costs us.

  2. You must filter the LST prior to using it for your samples. This is very important, as you don’t want someone else’s minerals mixing with yours. Cross contamination is a very serious issue and must be prevented. It is everyone’s responsibility to have clean and safe laboratory practices and nobody should have to clean up after you.

  3. You must check the density of the LST liquid before using it. For most purposes we will be separating sanidine/K-feldspar from plagioclase and quartz. The desired density for sanidine/K-feldspar separations is 2.582. Use the Hydrometer (using an graduated cylinder) to check the density. This value is important as to maximize the separation of sanidine/K-feldspar from the other phases. Please note however that not all sanidine/K-feldspar separations work at 2.582, so don’t be discouraged if your first try does not work. In the event this happens, you must make separate batches of LST with slightly different densities depending on the outcome of the separation that did not work the first time.

  4. Please note that the density of 2.582 will work for other K-bearing phases such as Adularia and K-feldspar from ore deposits, as well as volcanic and plutonic rocks.

  5. Upon completion of your heavy liquid separations you MUST clean the counter tops and all glassware. You should also filter all the heavy liquid.

  6. Check the density of the LST before each use. Density should be 2.582

  7. Pour a little bit of LST into the glass funnel.

  8. Pour your sample into the funnel. Be careful of material sticking to sides of funnel.

  9. Add more LST until you reach a quarter the way to the top of the funnel.

  10. Stir (if needed) the material in the LST liquid until there are no more clumps.

  11. Add more LST to the funnel to submerge all grains in the LST liquid.

  12. Put petri dish onto of funnel and let stand for approximately half hour. This step maybe longer when dealing with fine-grained mineral fractions.

  13. Once the minerals have separated you should have the following fractions a) float (sanidine/K-feldspar + glass if glass is still present in your sample); b) sink (quartz and plag); c) floaters (generally composite grains that don’t float or sink).

  14. Using the filter setup, drain the sink material into the filter medium. This step is critical!! You must do this without shaking the funnel as to minimize the mixing of the float material with the floaters and sink material.

  15. Wash the material on the filter substrate with DI water at least 4-5 times in a separate container to recover as much of the LST as possible.

  16. Repeat step 10 for obtaining the “floaters” and the float fraction. You can generally do this procedure for getting the sink and floaters in one fraction and the float material in another fraction. It depends on the amount of material you have to work with. Note! For the float fraction, there will be LST and crystals along the inside walls of the funnel…you will have to use DI water and rinse this off in the LST WASH container.

  17. Place drained (clean) LST liquid back into its container.

  18. Wash all fractions with cold tap water (rinse vigorously) a minimum of 15-20 times, then wash vigorously in DI water (Do not do this in the Ultrasonic bath). Its important that you rinse the outside and lip of the beakers to ensure that all LST has been removed.

  19. Let dry overnight.

  20. Pick between 20-50 crystals of what you believe are the sanidine/K-feldspar and make an oil mount using Oil of Wintergreen to check if they are all sanidine/K-feldspar. Remember the LST is not always a perfect separation of sanidine/K-feldspar due to inclusions, possible glass on grain margins, and composite grains of sanidine/K-feldspar/plag/quartz. See prior explanation of this topic.

Summary

A summary of the procedure

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